248 B. GRASSI AND A. SANDIAS. 
But this argument in its favour would be greatly weakened 
if the circumstance indicated by me above—namely, the pos- 
sibility of hereditary transmission by means of oviparous 
workers—should have played the part which I suppose it to 
have done. 
I determined, therefore, to investigate the origin of the 
workers and soldiers in Termitide,—in forms, that is, whose 
phylogenetic source is certainly absolutely distinct from that 
of the social Hymenoptera.) Such an inquiry would at 
least throw light on my hypothesis with regard to the bee, 
and in any case should lead to results of some utility for the 
problem I have several times referred to, the heredity of 
acquired characteristics, and for the subordinate and related 
question of the direct influence of environment on the gene- 
rative organs. 
The recent researches of Van Beneden, Boveri, O. Hertwig, 
and others on the ovum and spermatozoon had afforded yet 
another problem for solution, which would be modified accord- 
ing as to whether there should or should not exist special eggs 
or spermatozoa for the workers and soldiers of Termitidee. 
In short, the theory of evolution, the disputed heredity of 
acquired characteristics, and lastly, the theory which postu- 
lates the existence in every somatic cell of elements derived 
from both parents, these alike have all furnished me with 
motives for regarding the elucidation of the origin of caste 
forms in the social Termitide as a problem of the highest 
interest. This, then, is the main object of the present memoir, 
and it has been arrived at only by dint of prolonged observation 
and preliminary experimentation, the results of which are 
fully related here as a necessary corollary. 
The development of my argument has, so to speak, com- 
1 It must be recollected that, though we are acquainted with forms which 
perhaps can be ascribed to the Blattide from the Silurian strata, the Termi- 
tide, according to Scudder (in Zittel’s ‘Handbuch der Palaontologie,’ ii, 772), 
are absent in all the paleozoic, and appear only for the first time in mesozoic 
strata. Nevertheless the phylogenetic independence of the Termitide and 
Hymenoptera is indisputable. 
