Febbuaby 17, 1911] 



SCIENCE 



271 



thriocephalus infection acquired in this country. 

 It occurred in a woman who was born and has 

 always lived in Hennepin County, Minn., never 

 having been out of the state except once for a 

 visit to North Dakota. While there she ate dried 

 and smoked fish (otherwise uncooked) and it was 

 soon after her return home that she experienced 

 symptoms attributable to the tape-worm. The 

 infection must therefore have occurred in America 

 and from the eating of American fish. 



Paragonimus in a Oat in Minneapolis: W. S. 



NiCKEESON, University of Minnesota. 



I wish to put on record the occurrence of Para- 

 gonimus Kellicotti in the lung of a cat from the 

 grounds of the University of Minnesota. Three 

 specimens were obtained. 

 An American Intermediate Host for Bymenolepis 



dtminuta: W. S. Nickerson, University of 



Minnesota. 



The common tape-worm of the rat, Hymenolepis 

 diminuta, is also an occasional human parasite, 

 some fourteen cases having been reported. It has 

 been shown in Europe that its cercocystis stage 

 may be passed in several insects, the meal moth 

 and its larva (Asopia) , the earwig (Anisolabis) , 

 and beetles (Akis and Scauru^), Asopia being the 

 form that commonly serves as intermediate host. 

 In America an intermediate host has not been 

 observed and attempts at experimental infection 

 of our American meal-worms have not been suc- 

 cessful. 



A ease of infection of a child in Minnesota by 

 Hymenolepis diminuta has come to my attention 

 in which the circumstances suggested strongly 

 that the diplopod Julus had been the intermediate 

 host from which the child had become infected. 

 Acting upon this hint I fed fragments of Hymeno- 

 lopis dimiivuta to young diplopods, supposed at 

 the time to be young julids. Some of these were 

 found subsequently to be full of cercocystides 

 agreeing fully with those figured by Grassi and 

 Rovelli and which they demonstrated experimen- 

 tally to be the young of Hymenolepis diminuta. 

 Later I learned that my diplopods were Fontaria 

 Virginia Bellman of the family Polydermidse. 



In an attempt to repeat the experiment, using 

 Julus instead of Fontaria, I was able to obtain 

 but a single specimen of Hymenolepis diminuta 

 with but few proglottides having ripe ova. In 

 one of the specimens of Julus to which the pro- 

 glottides were fed a few specimens of cerocystides 

 were subsequently found which were of the same 

 sort as those previously obtained from Fontaria. 



The rearing of the adult worm ( Hymenolepides ) 

 from the larvae by feeding experiments was ren- 

 dered impossible in both cases by the fact that 

 the infected condition of the myriapods was not 

 discovered until they were already dead. In view, 

 however, of their complete agreement with the 

 descriptions and figures given by Grassi and 

 Rovelli of the larvae of Hymenolepis and the way 

 in which they were obtained there can be no 

 doubt as to their identity. 



These experiments show that at least two dif- 

 ferent genera belonging to the class Myriapoda 

 may act as intermediate hosts for Hymenolepis 

 diminuta in America. The intermediate hosts 

 previously known in Europe are of the class 

 Hexapoda. 



Preliminary Account of the Early Development 

 of Cirratulus grandis Verrill: John W. Scott, 

 Westport High School, Kansas City, Mo. 

 The common fringe-worm of the Atlantic coast, 

 at Woods Hole, is found in muddy ooze around 

 the roots of eel grass. It is easily excited to 

 oviposition, but few eggs will fertilize if deposited 

 before 10 P.M. Eggs deposited during the night 

 may be fertilized the next morning. The first 

 polar body comes off in 10 minutes, and the 

 second in 17 minutes. A yolk lobe is formed, 

 may be constricted ofi', but is always reabsorbed. 

 Unequal cleavage occurs at 49 minutes. The 

 second cleavage, 8 minutes later, results in a 

 three-celled stage. The entoderm appears to be 

 separated at the first cleavage. The entoderm cell 

 remains long undivided, and gastrulation takes 

 place by overgrowth of other cells. The trocho- 

 phore is scarcely able to leave the bottom and is 

 never pelagic. At 51 hours it settles on the ven- 

 tral side and moves like a flatworm; a ventral 

 band of cilia is used for locomotion. Septa de- 

 velop and disappear with the one exception found 

 in the adult. An introvert arises as an infolding 

 of the body wall posterior to the mouth; later a 

 common opening serves for both. The introvert 

 is used at this stage, chiefly for locomotion. The 

 larva was kept until 20 days old. 



An Accessory Chromosome in the Opossum: H. E. 



JOBDAN, University of Virginia. 



The number of chromosomes in equatorial plates 

 of dividing spermatogonia! and interstitial cells 

 equals seventeen. Plasmosome present in resting 

 primary spermatocyte. This stains intensely 

 black in iron-haemotoxylin, but only faintly green 

 in Auerbaeh's stain (^methyl green + acid fueh- 

 sin ) . Plasmosome can not be traced into later 



