1905.] On the Synapsis in Amphibia. 557 



from those in the (c) area in that they obviously contain more of the 

 apparently nucleola bodies scattered within the membrane. 



When resting cells of the region (b) are examined under a high power, 

 it is seen that nucleolus-like bodies visible under a lower power resolve 

 themselves into the short chromatic rods represented in figs. 2 and 3. 



These bodies are seen to lie more or less parallel to one another within the 

 cells, so that the appearance of the nuclei varies from that given in fig. 2, 

 where the chromatic rods are seen from one side, to that represented in fig. 3, 

 where the same rods are looked at from one end. 



The definite nature of these bodies is sufficiently obvious from the figures, 

 but their significance only became apparent upon ascertaining that their 

 number is always about 24; that is to say, it was found, after counting 

 in about 50 individual cells, that the number 24 was obtained for the great 

 majority, while in the few cases in which it was above or below this figure 

 such divergence was limited to one or two, and in nearly all these exceptions 

 it was possible to attribute the divergence to some optical difficulty. The 

 bodies lay over one another in the line of vision, or were hidden and 

 confused by the nuclear membrane and the like. 



The premaiotic resting cells in the testes of Triton are found then to contain 

 in their nuclei chromatic structures which at first might be, and generally 

 have been, regarded as " chromatin nucleoli " (Hemming) ; but they 

 correspond in numbers to the chromosomes of the premaiotic prophases and 

 division figures, for in this animal the number of the premaiotic chromosomes 

 is 24. These bodies correspond in fact exactly to what in 1904 we have 

 already described as the Anlagen of the premaiotic chromosomes in the 

 corresponding cells in the testes of Periplaneta,* and there can be no doubt 

 that they represent also the structures subsequently alluded to as prochromo- 

 somes by Overton,f Miyake,| and Strasburger§ in the same stage in certain 

 mono- and dicotyledonous plants. 



In Triton these structures are not restricted to the premaiotic cells of the 

 testis, but are equally apparent and have the same relationships in other 

 tissues of the animal's body. 



In some respects the bodies in question are more definite and stainable in 

 the resting premaiotic cells of Triton than they are in the corresponding 

 elements of Periplaneta, and in both cases their subsequent history during the 



* Farmer and Moore, ' Quart. Journ. Microsc. Sci., ; vol. 48, loc. cit, Plate 38 and text, 

 t Overton, J. B., ' Uber Beduktionsteilung in dem Pollenmutterzellen einiger Dikotylen.' 

 | Miyake, EI., ' Uber Beduktionsteilung in dem Pollenmutterzellen einiger Mono- 

 kotylen.' 



§ Strasburger, E., " Typische und Allotypische Kernteilung," ' Jahrb. fur Wiss. 

 Botanik,' vol. 42. 



2 S 2 



