14 



CYTOLOGY 



CHAP. 



resting nucleus at telophase, and reappear in the following prophase in 

 Ascaris, Salamandra and Allium respectively, as observed by different 

 workers. 



The following are the principal views held regarding these three 

 objects : 



(i) The telophase chromosomes undergo a process of vacuolation, by 

 which each becomes converted into a spongy cylinder ; this becomes 

 further decomposed into a loose spongework. The spongeworks formed 



A 



0»»tt^-- 



X 



■^ ( 



? 





„ t^j>HjF~_J;y__^^ ~ 



Fig, 6. 



Blastomere nuclei of Ascaris megalocephala, showing the evolution of a single spiral thread from each 

 telophase chromosome, and its reappearance as the prophase chromosome of the following mitosis. (After 

 Bonnevie, A.Z.,^ 1908.) A, B, telophase ; C, resting nucleus ; D, prophase. 



by all the chromosomes become indistinguishably merged into one 

 another, forming a " network of networks," which is the constitution 

 of the resting nucleus. In the prophase a reverse process takes place, 

 each chromosomal spongework becoming concentrated first into a spongy 

 band, and then into a homogeneous thread. Division of the chromo- 

 somes into daughter chromosomes takes place in prophase. [Van 

 Beneden and Neyt {iS8y) , Ascaris ; Boveri {igog), Ascaris ; Kowalski 

 (1904), Salamandra (Fig. 7) ; Gregoire (1906), Allium (Fig. 8).] 



(2) The telophase metamorphosis consists essentially in the formation 

 of long threads from the chromosomes ; the reticulum of the resting 



1 For the abbreviations used in references to certain journals, see p. 217. 



