ACCESSORY CHROMOSOMES IN MAN. 



liivalent types (compare Figs. i. i'>.m<l 11. 

 [3, 14. [5, P. and i; Thus while half of the spermatids receive 



. .iml hall" seven chromosomes, in terms of uni\ alence- the num- 

 ber- \\ould in all probability be ten and twelve r< ively. 



Ina-mn< h .1- tin- -(lermatids transform directly inio -|HTinato- 

 ii !<>1|(,\\ - th.it there must be be two classes of the latter diltt r- 

 uith r- to whether they have or do not have tin t\\. 



chpimo-oinrs. Thus the conditions in man appear t" be 

 much the -aim- that Wilson ('09) describes for .Vvrc 

 <>n< <|iia-li-biu lamily (Coreulze). 



\tiuii P. u- ;!> of such dimorphism of tin- -|H-rmai' 



ha\e I 'led iii various invertebrates, particularly in in- 



irachni apods, and it has Ix'en clearK dtni>n- 



-n.iiid Hi by spermatozoa which J>O-M -- thi- 



< hromosome group (there may lu-om , t\\<>, 

 tin. chromatic bodies, depending upon the 



1.|> ii >, those fertilized by spnin.n 



\\hirhd<i!i<>i [M)t>sess it, lop into males. Hence th< >!> 



me to id. il by some of our most careful and expe- 



workei in actual sex determinant. In any event it i- 

 o|i\inii-l> : \\ith tin- determination of sex either a- t.ui-. 



i In tin li^lit of numerous recent researches both .n 

 |ilani- and animal- tin- idea has rapidly gained ground that 

 ari-r- n. 'i .1- \\as lojig l>elieved, as a response of the developing 

 : IHHH t.i ^timuli from without, but that under normal condi- 

 tion- at least, il is automatically determined by some- internal 

 ph\ ii .il mechanism. 



Ina-inn. Ii a- [\\\> intricate matter has been repeatedly and ex- 

 haustive!) di-.n-M.l pro and con during the past ten year.- it i- 

 unncn---ar\ I"! in. to enter into a review of the subject anew. 

 Forth general reader who may not have kept in touch with the 

 current literature >f the subject, two excellent critique- are now 

 available in the recent papers of Wilson ('090) and Morgan '10 

 In tlu-e |aper- oii- will also find thorougliK"iiVv di-cu ion- . .1" the 

 subtle problem a.- to whether, assuming that th. sories are 



sex determinant-, the matter of sex determination i- to ! re^ardi-d 

 a- a qualitative pi effected by soi ne inherent peculiaritN' of the 



accesson i-hn>ino-. mu-. or whetlu-r the relation o| -uch .1 thro- 



