CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMU'TERA HETEROI'TERA. 99 



some, of its passage without division to one of the daughter cells. In reality such 

 processes are not acts of division at all, Ijut rather ones of separation, yet it seems best 

 to retain the long-accustomed terminology for them. And by " equational division " 

 is meant any division of a univalent chromosome ; this is always along the length of 

 an elongate element, and then probably always an equal halving; in the case of a 

 rounded chromosome it is practically impossible to determine the plane of the divis- 

 ion, except by an analysis of the changes of the chromosome in the early prophases, 

 when it can be demonstrated that even rounded chromosomes divide in a plane along 

 which they were previously elongated. 



Farmer and Moore (1905) have introduced the term " malotic phase," " to cover 

 the whole series of nuclear changes included in the two divisions that were designated 

 as heterotype and homotype by Flemming." But the older word "maturation 

 period " need not be given up, i)rovided we recognize that one of the maturation mito- 

 ses is always reductional. 



Finally, by the term " safraninophilous " I indicate that an element stains red 

 after the use of the triple stain of Hermann, safranine, gentian violet and orange G ; 

 and would again insist on the })()int that for the study of the allosomes this stain is in 

 a number of ways preferable to the iron htematoxyline method. 



I. Observations. 



PENTATOMIDM 



1. EuscHisTus variolarius Pal. Beauv. 



8i)ermat(jgonic Divisions. — Pole views of the equatorial plate stage show in most 

 cases 14 chromosomes ; the two smallest are not quite equal in volume and are the 

 diplosomes (J)i, di, Plate IX, Figs. 3, 4) ; the twelve others are autosomes which com- 

 pose 6 pairs of graduated volumes (A, a-F,f). But in one case there were clearly 15, 

 and this was illustrated in Fig. 3 of my preceding paper (1901 />) ; that earlier figure 

 erroneously showed 16 because I had mistaken one of the longest for 2. And now I 

 find two clear cases each with 16 chromosomes (Figs. 1, 2); the additional elements 

 are the ones marked G, <j. In both of these cells it will be noted that the compo- 

 nents of the pair G, r/ do not lie in the same plane, but that one is placed immediately 

 below the other, which would be a reason to conclude that the two are the pi'e- 

 cociously separated halves of a single one. These differences in number are puzzling, 

 and I have been unable to e.xplain them satisfactorily. But perhaps they are to be 

 interpreted as follows : the usual number of chromosomes is 14, Ijut occasionally there 

 is present an additional one which divides before the others, and thereby gives the 



