182 THE AMERICAN MONTHLY [October, 



sirable substances of the blood shall escape from it to the egg. Here we see 

 the follicle cells performing glandular work, for no true definition of a gland 

 can be framed which does not contain the physiological idea of the organ as 

 active in transferring substances from the blood to its cavity. We have, then, 

 clearly outlined before us the use of the follicle in producing eggs, in nour- 

 ishing them until they are built into the proper product for fertilization and 

 the initiation of a new course of development and the production of a new 

 generation. 



Turning to the egg' itself, we may briefly attempt to learn the uses of its 

 parts. The parts are the nucleus, the protoplasm, the deuteroplasm, and the 

 cell-wall. But when we see that the egg-cell with only a very slight amount 

 of additional substance of the spermatozoon is capable of such a wonderful pei-- 

 formance as the production of a cray-fish without any help from outside, it 

 being only requisite that the egg be kept in pure water and allowed air and 

 warmth, we must at once infer that the inside of the egg is not so simple as 

 intimated by seeing only the protoplasm, the nucleus, and the deuteroplasm. 

 If fact, it seems likely that no physical organism exists -which exhibits any- 

 thing comparable in complexity -with the physical mechanism of an egg 

 when it starts on its career of development. 



It is not proposed here to assert or to deny anything whatever regarding 

 a possible psychic factor which may or may not be present with the physical 

 mechanism which is present in the egg. The psychology of the cray-fish egg is 

 certainly reached at this point, but it is not the purpose of the present series of 

 articles to discuss it. Finally, then, what is the work performed by the nucleus 

 protoplasm and deuteroplasm? No answer in detail as to the work done by 

 each can be given. In the first place no one fully understands the structure 

 of these parts. One answer, however, is found which is practically agreed 

 upon by all students of the subject and which is reached by a study of the 

 destination of parts and of their behavior while at work. It is plain to all 

 that the material substance of the growing egg is derived from some recognizable 

 source. It is equally certain that this source is not the water outside the egg. 

 Hence it is necessarily within the egg itself. It is also well known that no 

 protoplasm, and much less any other substance, has the power of directing 

 chemical composition so as to produce the substance, of which protoplasm is 

 formed, except from a limited range of highly organized albuminous sub- 

 stances. Since the actual amount of protoplasm is constantly increasing and 

 must have a source, we should look for it in the deuteroplasm. We find this 

 constantly decreasing in amount, and we further find it actually in process of 

 digestion in eggs as soon as the digestive epithelium has arisen. Without 

 entering into all the proofs for the position, it may be stated as fully believed 

 as if a matter of fact in embryology that the purpose of the food-yolk is to 

 furnish material to build up cells before the time when the embryo will com- 

 mence foraging for this material. The work of the protoplasm and of the 

 nucleus is not so certainly known as is the use of the deuteroplasm ; yet, there 

 is practically a united assent at present to the assertion that the nucleus has 

 to do with the reproductive function, and with the production of new cells, 

 while the protoplasm has to do with the activity of the cell on its own per- 

 sonal account, so to speak. The behavior of nuclei everywhere seems to show 

 that their work consists in the production of two or more cells from one, while 

 the woi-k of the cell-protoplasm is to build up each of the two cells into the 

 mature cell-condition. Thus let us imagine a vorticella a full-grown ani- 

 mal. It sometimes grows by the division of its nucleus into two parts, fol- 

 lowed by division of the body ; thus two small vorticellse arise. Their next 

 act is to'grow to full size, and this appears to be by aid of the protoplasm. 

 Besides producing the growth the protoplasm is believed to be further con- 



