Germ Cells of Leptinotarsa Signaticollis. 193 



resting stage passes into a condition of almost complete disorgani- 

 zation from which it is able to recover its individuality and re- 

 appear in its characteristic form in the prophase of the first 

 maturation division. 



According to the strict individuality hypothesis these trans- 

 formations are to be explained solely by the remarkable proper- 

 ties possessed by the chromosomes as individual units. 



The results of the present study show that the nucleus and cyto- 

 plasm of the cell taken together constitute a unit ; while the chro- 

 mosomes are regarded as the expression of an organization of the 

 protoplasm of which they are a part. The occurrence of the ami- 

 totic period in the germ cells of both sexes clearly shows that this 

 organization is a property of the protoplasm as a whole; for it is 

 well nigh impossible to conceive of the chromosomes as independ- 

 ent entities, when during this amitotic cycle no provision is 

 made for their transmission from generation to generation. It 

 might be argued that in amitosis the chromosomes are divided 

 with as great precision as in mitosis; but actual observations do 

 not warrant such an assumption. 



One of the strongest arguments that have been used in favor of 

 the individuality hypothesis is the fact that in many cases at 

 least the size of the nucleus is dependent upon the number of 

 chromosomes that it contains. Thus Boveri ('05-'07) states that 

 in sea urchin larvse the surface area is proportional to the number 

 of chromosomes contained in the nucleus, and that nuclei possess- 

 ing an abnormal number of chromosomes pass on the abnormality 

 to the daughter nuclei. The general truth of this statement is 

 clearly indicated in the primordial germ cells of the ovary and 

 the testis of L. signaticollis where occasional abnormal mitotic 

 figures occur which result in the production of abnormal daughter 

 nuclei. 



Is it necessary to use the individuality hypothesis to explain 

 these phenomena? Could they not be as well explained by con- 

 sidering the chromosomes simply as a portion of protoplasm pos- 

 sessing a definite organization? 



During the last two or three decades the chromosomes have 

 received much attention and the results of the combined efforts of 



