MICROSCOPIC OBJECTS. 73 



curious spiral membrane. Many persons have supposed 

 this phenomenon to be the development or growth of the 

 seed. Tliis is readily shown to be a fallacy by the follow- 

 ing interesting experiment : — Cut off with a penknife a 

 thin shce of the testa, or covering of the seed ; place it 

 on a slip of glass under the microscope armed with a 

 power of about 50 diameters ; bring the object in focus, 

 and while in its place di'op upon it from a small glass tube 

 a httle water, then cover it with a plate of thin glass. 

 Attentively obsen^e your object, and in a few seconds the 

 membranous tubes will be seen to unroll themselves at 

 the edges. — They may be preserved by dropping a httle 

 gum-water upon them, and drying in that state. 



In vol. xix. of the Linnsean Transactions Mr. Kippis 

 informs us, that on the seeds of an Acanthodium from 

 Upper Egypt may be seen close-set seeming hairs ; but 

 which, when immersed in water, swell out, and become 

 broader, and then evidently consist of tufts of from 5 to 20 

 long, cyhndrical transparent tubes, which adhere to one 

 another for one-third of their length, and contain one, 

 two, and sometimes three spiral fibres, which are strongly 

 adherent to the membrane of the tubes. The fibres are 

 sometimes interrupted by rings. In the lower part, 

 where the tubes adhere together, the fibres are reticulated ; 

 towards the end the spirals lie asunder, and in the mid- 

 dle they are bound together by dehcate filaments given 

 off from the principal fibres. 



Vascular Tissue — presents the most varied and interest- 

 ing subjects for microscopic exammation. Spiral vessels 



