176 



SCIENCE 



[N. S. Vol. XL. No. 1022 



dried forms a very tough coat for the cyst. In 

 the case of Stylocephalus giganteus it seems 

 that the physiological character which makes 

 the cyst resistant to desiccation, even though 

 dehydration proceed to the distortion of the 

 cyst, is of value to this species in much the 

 same way as the protective envelopes of the 

 first two species. The host of Stylocephalus 

 giganteus is active throughout the winter on 

 warm days, so that this species does not have 

 to overcome the loss of host during the winter 

 months as does Gregarina rigida in the grass- 

 hopper, and Eleodes sp. have been taken in 

 December and January containing as many 

 gregarines as beetles of the same species taken 

 in August. These beetles are however dis- 



SEMI-PERMEABLE CAPSULES 



During a series of experiments to determine 

 the permanency of the fermentative reactions 

 of intestinal bacteria in stored waters, it be- 

 came necessary to use semi-permeable capsules. 

 A review of the literature failed to show any 

 method which was suitable for our purpose. 



As in McCrae's work, gelatine capsules 

 (size 00) are used as a basis for the coUoidin 

 capsule. A glass tube about 15 cm. in length 

 is warmed in the gas flame and pressed into 

 the closed end of the empty gelatine capsule. 

 The gelatine plug which inevitably forms in 

 the glass tube must be removed, at this point 

 by means of a wire, otherwise ruptures are 



T'/niaheJ Cajasv/e. 



Ca-jsisu/e attached 

 fo ghis roc/. 



Gelatin Ca/osu/e' ^Ce//oid,', 

 Fig. 1. 



tributed through a semi-arid region and the 

 favorite habitats of Eleodes spp., under stones 

 or at the bases of shrubby plains plants, are 

 quite dry for the greater part of the year, sub- 

 jecting the cysts of Stylocephalus giganteus 

 even though protected to some extent by the 

 excrement of the host, to considerable drying. 

 As shovra by the cysts under observation 

 moisture is essential to the completion of 

 sporocyst formation, since the cysts kept in 

 dry air did not reach the gray and black stages 

 until after they were placed in water. By 

 examination of the meteorological data for 

 eastern Colorado it may be seen that the 

 period of drying to which the cysts here con- 

 sidered were subjected, over four months, 

 exceeds the average droughts in this part of 

 the plains where Eleodes spp. are so exten- 

 sively parasitized. 



Max M. Ellis 

 XjNivEESiTY OP Colorado' 



liable to occur when the capsules are boiled 

 later. 



The union of the capsule and the glass rod is 

 made airtight by coating the union with a 

 twenty per cent, solution of gelatine by means 

 of a small brush. The layer of gelatine is ex- 

 tended up the glass tube for a distance of 

 about 4 cm. If the two halves of the capsule 

 do not fit tightly, it is advisable to paint them 

 also with the gelatine. 



After thoroughly drying, the capsule is 

 dipped into the colloidin solution (coUoidia 

 1 part, ether IJ parts and alcohol Ij) until a 

 proper thickness is attained, which may be 

 judged by holding the capsule before the light. 

 Experience has shown that at least four dip- 

 pings are necessary. It was found that the 

 finished capsules were often weak at the point 

 where the halves of the gelatine capsule meet. 

 This point was strengthened by allowing addi- 

 tional coUoidin to collect at this place. The 



