44 STUDIES IN SPERMATOGKNESIS. 



i 



seen in figures 193-197 (plate xiu). This would seem to be a favorable 

 form for determining the chromosome conditions in somatic cells, but 

 no clear equatorial plates were found in either larvae or pupae. 



In Cicindela primeriana (family Cicindelidae) there are 18 chromo- 

 somes in the spermatogonium (fig. 198), one being small. The hetero- 

 chromosome group is blended into a vacuolated sphere in growth 

 stages (figs. 199, 200). In the metaphase of the first division it is 

 trilobed, or tripartite (fig. 201), and in metakinesis, a small spherical 

 chromosome separates from a much larger V-shaped one (fig. 202). 

 Equatorial plates of first and second spermatocytes are shown in 

 figures 203 and 204. Whole cysts of giant first spermatocytes were 

 found both in growth stages (fig. 205) and prophases (fig. 206). Here 

 the heterochromosome group is plainly double (fig. 205), and the con- 

 ditions observed must have been due to the failure of a spermatogonial 

 mitosis to complete itself. 



Several of the Carabidse have been studied, and the material, 

 though not especially favorable, is interesting in that some members of 

 the family have an unequal pair of heterochromosomes, others an odd 

 one. Chl&nius cestivus (figs. 207-212), Chlanius pennsylvanicus (figs. 

 213-215), and Galerita bicolor (fig. 216) have the unequal pair, while 

 Anomoglossus emarginatus (figs. 217-223) has an odd heterochromo- 

 some (x), which behaves exactly like the larger heterochromosome in 

 other carabs. 



In the Elateridae and Lampyridae we also have examples of the 

 second type with the odd chromosome. Two Elaters, species not 

 determined (figs. 224-229 and 230-235), have each 19 chromosomes 

 in the spermatogonia (figs. 224 and 230), and in the first spermatocyte 

 division an odd chromosome (x) which is in each case the smallest. 

 In the first of these Elaters, the female somatic number was determined 

 to be 20 (fig. 229). In the second Elater the pairs of second sperma- 

 tocytes, containing 9 and 10 chromosomes respectively in the two 

 cells, were in nearly every case connected as shown in figure 235, 

 one pair of chromosomes not having separated completely in the first 

 mitosis. Of Ellychnia corrusca (family Lampyridae) only the sperma- 

 togonial equatorial plate, containing 19 chromosomes (x, the odd one) 

 is given, as no material in maturation has yet been obtained, and a 

 comparative study of the germ cells of the Elateridae and Lampyridae 

 will be made as soon as suitable material can be secured. 



In addition to the species of Coleoptera described here, two others, 

 Coptocycla aurichalcea and Coptocycla guttata have been studied by one 

 of my students and the results published elsewhere (Nowlin, '06). In 

 both an even number of chromosomes (22, 18) was found in the sper- 



