No. 642] VABIAT/nX l.\ c II A J! ACT /■ US 



53 



normal ratio or balance. This stamp collector carries 

 his collection around with him, and it fills two big, coat 

 pockets, a trousers pocket, and there are even a few in his 

 vest pocket. But unlike most collectors this one has 

 never taken the trouble to sort over more than a few of 

 his stamps. Meanwhile he strings them together pretty 

 much hit or miss. This stringing stamps together is 

 rather disapproved of by some other stamp collectors, 

 who think that is no way to treat stamps, and each of 

 whom has his owm favorite method of arranging them. 

 Because of this hit or miss method of making the strings 

 of stamps the ratio among the different grades of redness 

 of Russian stamps is different in different parts of the 

 strings, and so if some other ardent collector should snip 

 off a piece of one of the strings and carry it away, the re- 

 mainder of the Eussian stamps might have a considerably 

 redder tone, while at the same time the Polish stamps 

 might become bluer. If a whole string were lost, then 

 many of the sets of stamps might have quite different 

 complexions. 



Now I have been recentl\' studyinu' llic effects of the 

 loss of one of the chromosomes of DrosophilaA namely, 

 the small round fourth-chromosome, and the phenomena 

 offer striking parallels to those of dioecious sex, including 

 sex-linked inheritance and sex-limited characters. Indi- 

 viduals having only one fourth-chromosome show a 

 change in many characters, among wliicli may l)c men- 

 tioned smaller size, smaller bristles, later hatcliinu'. i)oorer 

 viability, paler body-color, darker trident iiatteni, shorter 

 blimtei- wings, etc. Each of these (litVcrences corre- 

 S])()n(ls to a cliaracter foi' which tlic fourth-chromosome 

 was internally unbaianced, lliat is, tor wiiich the ratio of 

 plus to minus modifiers was ditTerriit from that of the 

 whole group. For all of the cliaraetci-.^ in which there 

 was an internal preponderance of pins nio(]ilicr> the 

 grade will be shifted in a minns dli-cction by the loss of 

 the fourth-chromosome, for example, tiic shorter wings 

 and paler body-color. Likewise the chai-actei's that shift 

 in a plus direction, as the darker tri(h'nt pattern and the 

 large eyes, are characters for which tlie fonrth-chi-oino- 



