304 SUMMARY OF CURRENT RESEARCHES RELATING TO 



caution, " feigning death," and holding on to twigs, when attacked by 

 the ants. It seeks a mate and copulation occurs. The beetles frequent 

 birch shrubs, eating the young shoots and leaves. The female seeks a 

 tree or shrub above or close to a nest of F. rufa, and drops the eggs on 

 the ground beneath. The eggs are covered by an oxcrementitious case 

 or capsule, each like the end of a birch catkin. The ants carry the 

 covered eggs to the nest, probably mistaking them for vegetable refuse. 

 The young larva, which hatches in about twenty-one days, uses the egg- 

 case as a nucleus on which to build the larval case, — made of the larval 

 excrement mixed with earth. To enlarge the case the larva removes 

 particles from the inside and plasters them on the outside. The larva 

 feeds on vegetable refuse in the nest and may possibly be of some 

 service to the ants in removing useless or decaying stuff. The beetle 

 looks like a mimic of Coccinella distincta, which also lives in nests of 

 Formica rufa, and it is distasteful on its own account, thus affording an 

 example of Miillerian mimicry. 



B. Myriopoda. 



Spermatogenesis and Oogenesis in Lithobius forficatus.* — Carl 

 Tonniges has reached the following conclusions. (I.) As to spermato- 

 genesis : — In the young male gonads numerous elements unite to form 

 a syncytium ; this is due to emigration of indifferent cells from the 

 germinal epithelium which furnishes the specific spermatogonia ; most 

 of the syncytium is used as nutrition for the primitive sperm-cells, but 

 some of the spermatogonia are utilised by their neighbours. The 

 nutritive cells of the Lithobius testes are really abortive germ-cells. 



The spermatogonia proliferate as cell-complexes into the syncytium 

 of the testis. They form long cell-strands with nuclei disposed one 

 behind the other. As the elongation goes on, these nuclei acquire cell- 

 boundaries. All the nutritive cells are absorbed. 



The cell-lineage is as follows : — 



"B* 



Indifferent cells of the germinal epithelium 



Geim-cells Indifferent nutritive 



(syncytium) cells 



Spermatogonia Abortive spermatogonia 

 (nutritive cells) 



(II.) As to tho oogenesis, the general results are as follows : — In the 

 young female gonads, as in the terminal chamber of the insect's ovarian 

 tubes, all the cell-elements form a syncytium. This syncytium is in 

 greater part utilised as nutritive matorial by the ova which grow over 

 it like parasites. The origin of the syncytium is due to the emigration 

 and separation of indifferent cells from the germinal epithelium. From 

 this indifferent cell-material there arise germ-cells, which become ova 

 and nutritive cells. Besides these it gives rise to follicle-cells. Typical 



* Zeitschr. f. wiss. Zocl, Ixxi. (1902) pp. 328-58 (2 pis. and 3 figs.). 



