AMITOSIS IN THE MALPIGHIAN TUBULES OF THE 

 WALKING-STICK (DIAPHEROMERA FEMORATA). 



WM. S. MARSHALL. 



Schindler x in his paper on the Malpighian tubules of insects 

 describes both direct cell division and budding of the nucleus. 

 In amitotic division he notes a regular form in which the nucleus 

 is first cut in two and then followed by the cell (in Sarcophaga 

 carnaria), and also, in Lophyrus pini, a. peculiar method in which 

 the division passes from one side of the nucleus towards the other. 



While working on the anatomy of the walking-stick it was 

 often noticed, in studying sections through different parts of the 

 body, that mitotic figures were quite abundant. In looking over 

 serial sections cut through the head, thorax, or abdomen, mitosis 

 was often observed in cells in the fat, tracheae, epithelial cells of 

 the ovarian tubules, etc., but nothing of the kind was ever seen 

 in the Malpighian tubules. Later, all the slides in which any Mal- 

 pighian tubules could be found, were reexamined in an endeavor to 

 find dividing nuclei. Other slides were then prepared, both sec- 

 tions and entire tubules, etc., and, while no mitotic figures could 

 be found, some nuclei dividing amitotically were seen. 



Attention has already been called 2 to the two kinds of Malpig- 

 hian tubules in Diapheromera femorata ; these differ in their size 

 and in their position within the body of the insect. . In both kinds 

 of tubules the cells are binucleate. 



The greater part of the material used was taken from mature 

 or nearly full grown insects. Tubules were also prepared from 

 a number of walking-sticks about one third full grown. Besides 

 these two stages a number of the insects were hatched out in the 

 laboratory and the tubules taken from some which were not more 

 than four to six days old. Embryos in which the tubules had 

 developed were also sectioned. This gave four different stages ; 



1 E. Schindler, " Beitrage zur Kenntniss der Malpigi' schen Gefasseder Insecten," 

 Zeit. wiss. ZooL, Vol. XXX., 1878. 



2 W. S. Marshall and H. H. Severin, "Ueber die Anatomie der Gespenstheu- 

 schrecke, Diapheromera femorata" Arch. Biontol., Vol. I., 1906. 



