We started with an onion from the outside.  First there’s a dried up layer or ‘tunic’ that we don’t eat.

<figure aria-describedby="caption-attachment-40385" class="wp-caption alignnone" id="attachment_40385" style="width: 300px">
 <a alt="tunic-of-onion-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/tunic-of-onion-1.jpg">
 <img alt="tunic of onion" class="wp-image-40385 size-medium gcloudimg" data-attachment-id="40385" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="tunic of onion" data-recalc-dims="1" height="169" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/tunic-of-onion-1.jpg" width="300"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40385">
 Tunic of onion
 </figcaption>
</figure>
<figure aria-describedby="caption-attachment-40381" class="wp-caption alignnone" id="attachment_40381" style="width: 300px">
 <a alt="onion-tunic-under-foldscope-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/onion-tunic-under-foldscope-1.jpg">
 <img alt="onion tunic under foldscope" class="wp-image-40381 size-medium gcloudimg" data-attachment-id="40381" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="onion tunic under foldscope" data-recalc-dims="1" height="225" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/onion-tunic-under-foldscope-1.jpg" width="300"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40381">
 Onion tunic under foldscope
 </figcaption>
</figure>

 The cells in the tunic must be dead. Even the cell walls are disintegrated, quite unlike
 <a href="https://microcosmos.foldscope.com/?p=39694">
 the dead xylem cells that we saw in matchsticks
 </a>
 . Later we found,
 <a alt="indexmag.html" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/indexmag.html">
 in the wonderful Walter Dioni’s website, that we might also see crystals of calcium oxalate and other chemicals in the tunic of the onion
 </a>
 . That is for other times.


 Next below it was a semi-dried layer which too we often discard.

<figure aria-describedby="caption-attachment-40383" class="wp-caption alignnone" id="attachment_40383" style="width: 169px">
 <a alt="semi-dried-layer-of-onion-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/semi-dried-layer-of-onion-1.jpg">
 <img alt="semi dried layer of onion" class="wp-image-40383 size-medium gcloudimg" data-attachment-id="40383" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="semi dried layer of onion" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/semi-dried-layer-of-onion-1.jpg" width="169"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40383">
 Semi-dried layer of onion
 </figcaption>
</figure>
<figure aria-describedby="caption-attachment-40384" class="wp-caption alignnone" id="attachment_40384" style="width: 225px">
 <a alt="semi-dried-layer-under-fold-scope-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/semi-dried-layer-under-fold-scope-1.jpg">
 <img alt="semi dried layer under fold scope" class="wp-image-40384 size-medium gcloudimg" data-attachment-id="40384" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="semi dried layer under fold scope" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/semi-dried-layer-under-fold-scope-1.jpg" width="225"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40384">
 Semi-dried layer under foldscope
 </figcaption>
</figure>

 In this layer the cell walls still remain somewhat visible.


 Now come the nice fleshy layers of onion, or ‘scales’. You can remove the skin, or ‘epidermis’, from the outer or the inner side of each scale. The textbook tells us to take the inner epidermis but we tried both sides, about 3 samples of each. The outer epidermis of all the scales was pinkish in color and did not stain so easily. But it did have a nice surprise for us!

<figure aria-describedby="caption-attachment-40377" class="wp-caption alignnone" id="attachment_40377" style="width: 300px">
 <a alt="inner-and-outer-epidermis-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-and-outer-epidermis-1.jpg">
 <img alt="inner and outer epidermis" class="wp-image-40377 size-medium gcloudimg" data-attachment-id="40377" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="inner and outer epidermis" data-recalc-dims="1" height="287" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-and-outer-epidermis-1.jpg" width="300"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40377">
 Inner and outer epidermis
 </figcaption>
</figure>

 Here is the outer epidermis of one scale:

<figure aria-describedby="caption-attachment-40382" class="wp-caption alignleft" id="attachment_40382" style="width: 256px">
 <a alt="outer-epidermis-of-onion-scale-under-foldscope-1-e1528800307734.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/outer-epidermis-of-onion-scale-under-foldscope-1-e1528800307734.jpg">
 <img alt="outer epidermis of onion scale under foldscope" class="wp-image-40382 size-medium gcloudimg" data-attachment-id="40382" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"1"}' data-image-title="outer epidermis of onion scale under foldscope" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/outer-epidermis-of-onion-scale-under-foldscope-1.jpg" width="256"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40382">
 Outer epidermis of onion scale
 </figcaption>
</figure>













 Here is the inner epidermis:

<figure aria-describedby="caption-attachment-40378" class="wp-caption alignnone" id="attachment_40378" style="width: 300px">
 <a alt="inner-epidermis-of-onion-scale-under-fold-scope-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-of-onion-scale-under-fold-scope-1.jpg">
 <img alt="inner epidermis of onion scale under fold scope" class="wp-image-40378 size-medium gcloudimg" data-attachment-id="40378" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="inner epidermis of onion scale under fold scope" data-recalc-dims="1" height="225" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-of-onion-scale-under-fold-scope-1.jpg" width="300"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40378">
 Inner epidermis of onion scale
 </figcaption>
</figure>
<figure aria-describedby="caption-attachment-40379" class="wp-caption alignnone" id="attachment_40379" style="width: 225px">
 <a alt="inner-epidermis-of-onion-stained-under-fold-scope-1.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-of-onion-stained-under-fold-scope-1.jpg">
 <img alt="inner epidermis of onion stained under fold scope" class="wp-image-40379 size-medium gcloudimg" data-attachment-id="40379" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="inner epidermis of onion stained under fold scope" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-of-onion-stained-under-fold-scope-1.jpg" width="225"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40379">
 Inner epidermis stained with methylene blue
 </figcaption>
</figure>
<figure aria-describedby="caption-attachment-40380" class="wp-caption alignnone" id="attachment_40380" style="width: 222px">
 <a alt="inner-epidermis-with-dark-feild-labeled-1-e1528800430708.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-with-dark-feild-labeled-1-e1528800430708.jpg">
 <img alt="inner epidermis with dark feild labeled" class="wp-image-40380 size-medium gcloudimg" data-attachment-id="40380" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"1"}' data-image-title="inner epidermis with dark feild labeled" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/inner-epidermis-with-dark-feild-labeled-1.jpg" width="222"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40380">
 Inner epidermis with dark field
 </figcaption>
</figure>

 The dark field image is taken with a finger in front of the camera lens held in sunlight. In it the nuclei are seen clearly, better than in the stained slide.


 We found that the cells of the inner epidermis were fairly uniform in shape and size. In the outer epidermis the cells were of different shapes and sizes. We were further surprised to find
 
 stomata
 
 in the outer epidermis!
 <a alt="indexmag.html" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/indexmag.html">
 Again, Walter Dioni told us
 </a>
 , the scales are actually modified onion leaves. If the scale grew out into a leaf then its outer epidermis would become the lower epidermis of the leaf. That’s why the outer epidermis of each onion scale has stomata and the inner one (usually) doesn’t.


 Onion cells are larger than most plant cells:
 <a alt="how_big_is_a_cell.pdf" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/how_big_is_a_cell.pdf">
 the average size of onion skin cells is about 400 microns
 </a>
 . In comparison,
 <a alt="Cell_size" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/Cell_size">
 most other plant cells are between 10-100 microns in size
 </a>
 .


 Onion is
 
 Allium cepa
 
 . We also looked at garlic, or
 
 Allium sativum
 
 . There is just one epidermis surrounding the garlic clove, which is actually a bulb. This is what it looked like.

<figure aria-describedby="caption-attachment-40376" class="wp-caption alignnone" id="attachment_40376" style="width: 286px">
 <a alt="garlic-outer-layer-under-fold-scope-e1528800483963.jpg" class="gcloudimg" href="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/garlic-outer-layer-under-fold-scope-e1528800483963.jpg">
 <img alt="garlic outer layer under fold scope" class="wp-image-40376 size-medium gcloudimg" data-attachment-id="40376" data-comments-opened="1" data-image-meta='{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}' data-image-title="garlic outer layer under fold scope" data-recalc-dims="1" height="300" src="https://storage.googleapis.com/microcosmosdelta.appspot.com/images/transfer_40389/garlic-outer-layer-under-fold-scope.jpg" width="286"/>
 </a>
 <figcaption class="wp-caption-text" id="caption-attachment-40376">
 Epidermis of garlic clove
 </figcaption>
</figure>

 Bhavya Sahithi (
 <a href="https://microcosmos.foldscope.com/?author=2620">
 Bhavya on Microcosmos
 </a>
 )


 Jayashree Ramadas

Onion outside in

TCIS Outreach | Tue, Jun 12, 2018, 4:53 AM

Locations

Categories

Type of Sample

Foldscope Lens Magnification

Comments