A DISCUSSION OF CYCLOP> YIRI!>I> J URINE. 2Q5 



of the European form. The specimens I have met with have 

 in-ver been o\ < r i .5 mm. in length and are much more frequently 

 between 1.2 mm. and 1.4 mm. long. 



1 In- drawings in the accompanying plate also show the dis- 

 parity in sj/e lit-t ween the American and the European forms, 

 that of the fifth foot of the European variety, from a specimen 

 in in\ |i< ^session, being drawn to a scale half of that of the other 

 drawing 



Is it noi possible iliat we have here .1 case similar to that which 

 k l\. Gates ('09) discovered \\\ il-jwtlu'ru.' (Enothcm zi'^i*. a 

 uiant mutant of (>. [jinuirckintm, was found to possess - s i hromo- 

 SOmes or double tin- number of tin- parent form (I-J 1 . It-- cells 

 were found to be correspondingly larger. Gates su{ 1 that 



in an egg of < ). I.nnnirck'nuKi a double number of chromosomes 



arose from a division of the chromo-ome- unaccompanied \<y 



1 1 u< I ear and cell di\ i-i<ni -ooii after fert ili/at imi ami that thi^ 



de\ eloped into llle ( >. ^/\'(/.V lorill. 



Either ( '. f>n re its <>r the European ( '. ririili* ma\ conceit ably be 

 a m in at ion one of the other if. in tin- mu- ca-e. all o| the ehrom< >- 

 -ome- -plit into hakes \\iihout siib-e<]ueiit nuclear dixisjoii. or, 

 in tin- other, go into mitosis without splitting SO as to prodm e 

 the numbiT 12 for the Eiiiopi.ui :iri<Iis or (> for the American 

 f)(ir<ns. The cells of the European i'iriilis < oiiiainin^ tueke 



chromosomes would then be twice the size ol those ot < '. f><ir<-ns 



\\hich ha- only H\. The .ictual di-cre| >aiicv in -i/e bi-twi-en the 

 t\\o forms could llnis be explained. 



Nob Since the above was senl to the printers I ha\ e secured 

 specimens of a ( 'y< !<>t>* riridi.s tr. -m several pools near Edgewater, 

 \ 1 l IHA are mostly from 2-3 mm. in length although several 



inaiuie indixiduaU mea-niv only 1.4 mm. 



\oi onk do the\ re-emble I he t \pical luim] u-an riridis J urine 

 in si/e; in the ciliated inner margin of the furcal rami; in the 

 tilth tool \\ith the \ er\ small barely jointed spine , , n the second 



IH-IU ; but aUo in ilu- --\n\\c formula for the four swimming 



feet which is 2, 3, 3, 3; and. most si-m'licant of all. in the .shape 

 of the seminal receptacle, the figure shown in the table f.-r the 

 European I'iricli.s being an exact picture of the same organ in tin- 

 form under discussion. 



