ACCESSORY CHROMOSOMES IN MAN. 22 \ 



old in. iii-rial. - the number of chrumnsom \\vmy- 



foiir. He < ites tin- papers of Hansemann ('91, '93 as the earlie-t 

 attempi- kn.\vn to him to make a count of the fhn>m<>nu-- of 

 man. Bui sin< e 1 l.msemann records eighteen in one case, twenty- 

 four in another, and forty in a third, the latter apparently 



:nattd Irom the spireme stage, and inasmuch as he him-elt 

 admit- ihat his count was very uncertain, concluding with the 



-nient that, "die Zahl sicher holier als 24 sei," we may fairly 

 di -regard it. I think, in the light of modern technique. In this 



ml papi r 1 lemming ('97) states that his count i- ba-ed <>n 

 iinl\ ti.ur cell-divisions in which the chromosomes had ju-t 

 split preparatory to separation. His exact statement of hi> 

 ol,--r\ ations is as follows: "Es gelang das zwar bei keinen 

 >i< her. alx-r bei zweien der vier darin enthaltenen Mito-< n 

 ann.iheriid ; es scheinen in beiden I'iillen 24 Doppelchromosomen 

 zu sein. Bei beiden sind es jedenfalls mehr als 22 und. \\ ie ich 



n /u konnen glaul>e, weniger als 28; an einigcr Stellen di ( ken 

 sie sich so, dasx eine exacte Zahlung mir unmoglich \\ird." 

 I ! -mining's material had IK.VII fixed in one sixth per cent, chromic 



I and stained \\ith safranin. 



Kirdelelx-n has published thn-e paj>ers ('92, '97, '^s ' mi 



the spermatogenesis of mammals including man in which he 



comes l> the conclusion that the number of chromosomes in 



the spermatogonia and siK-rmatocytes of man are sixteen and 



ectively, and in his later pajKTs he sets down four 



as i lu nnmlH-r that ultimately reaches the spermatids. That is, 



there i- in successive divisions a reduction in numbers from six- 



ijn and then from eight to four. This is much the 



lit ion thai I have found prevailing in birds (Guyer, '02, '< 

 \\ilc.'\ ulied sections from a testis which had been re- 

 moved 1 1 oin a man lit ty-four years old, in an operation for hernia. 

 Alihon'ji -,T,, i al swelling had existed for a year previous to tin- 

 operation the te-tis seemed to be normal in size and appearan.v. 

 He repon-, that, "In my material the number seemed to be 



iteen, the difterent counts resulting in ti ran-in^ troin 



titteeii to nineteen." lie remarks howc\'er u|n the Mrikiii^ 

 absence, of kar\okinetic stages, so that his ob-ervation-, were 

 ba-ed upon a \er\ limited number ot di\-i>ion>. liec.m-e of 



