Insects. 4497 



the animal kingdom, high or low, a definite and invariable arrangement. 

 Then again as to the constitution of each and both being on the whole 

 of nucleated cells, it may be said that it could hardly be conceived to 

 be otherwise, for nucleated cells are the elementary components of all 

 functional organized forms ; and it may be added, moreover, that he 

 knows little of the highest physiology who has not learned that widely 

 different teleological significations may be concealed beneath isomor- 

 phic animal forms. 



I have thus dwelt rather lengthily upon this point, because I think 

 it is a vital one in our subject, and the possession of clear ideas thereon 

 will be found singularly conducive to our correct appreciation of the 

 whole class of anomalous phenomena under discussion. But we will 

 revert to the subject of Owen's hypothesis. 



As to the chief point in this hypothesis, the continuation of the 

 primary germ-mass as a leaven, from brood to brood, it requires but 

 little thought to perceive that it is physically impossible. I would 

 first allude to Owen's statement, quoted above, that a portion of the 

 germ-mass is taken into the abdomen of the embryo Aphis, and, as he 

 thinks, assumes, without any change, the position of the ovarium. By 

 this he refers, undoubtedly, to the vitellus-looking mass I have 

 described in my observations, and according to which, also, it ap- 

 peared to serve only as the nutritive material out of which the 

 digestive organs and the germs are formed. Moreover, I feel quite 

 sure that the germ-cells are new cells formed in the abdomen, and not 

 those derived from the parent. But the point I wish to enforce is, 

 that even admitting that individuals B may contain an actual residue 

 of individuals A, it is clearly evident that this succession must stop 

 with brood B ; for these residual germ-cells which compose B in its 

 earliest condition are lost in the developmental processes, and the 

 germs of individuals C, which are found in B, are each, primarily, 

 nucleated cells formed de novo, as I have observed, and above 

 described. With these observed conditions of development, it is im- 

 possible for the individuals of the successive broods to inherit the 

 original spermatic force in the continuation of the original cells. 



The hypothesis of Owen, therefore, plausible and ingenious as it 

 may seem, does not appear to me to accord either with observed facts 

 or with the soundest physiology of the reproductive processes. I may 

 here remark, also, that his doctrine of Parthenogenesis, based as it is 

 upon the conditions of the hypothesis in question, cannot, as such, be 

 sustained, for the same reasons, and all its phenomena would appear 

 to find their solution either in Steeenstrup's doctrine of " Alternation 



