52 THE OVUM AND 



part of which flows slowly out. Around this mass lies a more 

 consistent, cohering, membrane- like stratum, which lines the 

 cavity of the little egg. When a portion of this mass is exa- 

 mined under the microscope, a great many round and very trans- 

 parent vesicles or cells are observed in it, each of which encloses 

 a dark corpuscle resembling an oil-globule. Many such globules 

 float about free, and in addition to them there is also a good 

 deal of minutely granulous substance present. In order, how- 

 ever, to examine this mass in a perfectly natural condition, the 

 use of water must be avoided ; one of the little eggs, of from 

 half a line to a line in diameter, should be placed upon the dry 

 object plate, and then pierced, a drop of its contents being 

 allowed to flow out. This drop will be found to consist entirely 

 of very pale cells, most variable in size, each one containing a 

 round globule, the size of which is about proportionate to that 

 of the cell. This globule or nucleus resembles an oil-globule, 

 in consequence of its dark outline, (see pi. II, fig. 3.) Many 

 of these cells with their nuclei are so small, that, when lying 

 close together, they might be regarded as a merely granulous 

 substance ; the cells may, how r ever, be recognised with a fa- 

 vorable light. Some of the larger ones occasionally contain 

 two or three of the globules or nuclei before mentioned. The 

 contents of the cells are usually quite transparent, but some 

 isolated ones are seen, in which a minutely granulous precipi- 

 tate has formed. These cells are enclosed within the egg, in 

 a small quantity of transparent fluid. In order to explain the 

 somewhat variable appearance which the contents of the egg 

 assume after contact with water, a small one should be placed 

 upon a glass with a drop of that fluid, and some of its contents 

 pressed out whilst under the microscope. A quantity of these 

 cells will then be seen to burst quite suddenly in the water, 

 precisely like soap-bubbles in the air. In consequence of their 

 paleness, the fact of the bursting is rendered manifest, in the 

 first instance, only by the sudden motion of the nucleus, which, 

 together with some minutely granulous substance, remains 

 behind. If these cells were solid, although ever so soft, this 

 sudden bursting would not be possible. They are therefore 

 true cells. I cannot say whether the globule enclosed in them 

 is to be regarded as the nucleus. Although it resembles an 

 oil-globule, it does not appear to be fat ; for if acetic acid be 



