THE SPERMATOGENESIS OF EUCHROMA 



GIGAXTEA. 



M. LOUISE NICHOLS. 



Tin- lar^e-4 of the huprestid beetles, Eitchroma gigaiitcn. i- 

 n;iti\c to Central and South America and is commonly found 

 sunning it -elf on the trunks of trees. In such situations tin- 

 ties are not difficult to capture, as their movements are 

 rather -lir^i-h until they become thoroughly alarmed. The 

 -pei imen- trom which the present study was made were taken 

 at ( nlel.ra. Panama, in the month of August, at which time 

 some "I i In- l>eetles were mating, the male apparently attracting 

 tin ti in, ill- by a clicking sound produced by the elytra. 



I pi MI M-< -i inning the testes, I was surprised to find a complete 

 verie- nt -t.e^es from the spermatogonia to the mature sperma- 

 tozoa, tin- \niinger stages not being confined to the larva,- <>r 

 pnp.e. .1- i- ln-i|iu-iitly the case in insects. The testes were fixi ! 

 in ( lil-nn's mi nuro-acetic-nitric solution or in Fleming's strong 

 -olution and stained with iron-luematoxylin or with saffranin 

 ami malai hite green. 



In i In- development of the germ cells of insects, as is well known 

 through tin- results of the researches of Montgomery, Wilson, 

 Stevens and others, there are present chromosomes which have 

 been lallnl heterochromosomes or idiochromosomes. Wilson 

 (1909 ha- slin\\n for the Hemiptera that in certain forms tin- 

 idiochromosomes are equally well developed in both sexes, in 

 oilier- the male possesses one well developed, the other rediK-'l 

 in si/c, \\hiU- in still others one is entirely lacking in the malf. 

 Mr\<-n- [906 t ound somewhat similar conditions in the Coleop- 

 tera. llm-. tin l^laterida? and Lampyrida- possess only ilu 

 in Id i-hn uni -si unes. while the families Chrysomelida?, Cocci- 

 nelidae, Scarabidae, Silphidae and Buprestida- show one of tin- idin- 

 clii-oino-i'ini-s reduced in size. In Carabida^ some nu-nil'-r- 

 have an unequal pair of heterochromosomes, others an odd 

 din >nu !- mie. Enchroma gigantea, as a member of the taniih 

 Hupu-stida-. belongs in the second of these groups (Figs. 21-22). 



167 



