48 NATURAL SCIENCE. January. 



many unfertilised ova are deposited : the larger cells excite the queen 

 and furnish a stimulus which causes the spermatheca to contract and 

 expel spermatozoa, so that all large cells contain fertilised ova, of 

 which the great majority give rise to queens. The explanation is 

 ingenious, but does not appear to reach the bottom of the matter. 

 It is probable that the explanation of the phenomena is the same for 

 both bees and wasps, and, if so, the question arises, — how is it that the 

 large drone-cells of bees do not act in the same, but in the contrary 

 manner, on the nervous system of the queen bee ? It is tempting to 

 attribute the sure fertilisation of ova towards the end of the season to 

 the elongation of the abdomen of the queen wasp in order to reach 

 the bottom, or rather top, of the large cells ; such elongation would 

 cause a narrowing of the abdomen and put some pressure on the 

 walls of the spermatheca. A similar view has been held with regard 

 to the queen bee, but this supposition is effectually disposed of by the 

 observations of Drory and others, that the queen bee will lay drone- 

 ova in small cells if all large are removed, and, conversely, fertilised 

 eggs in large cells if provided only with the latter. Incidentally it 

 may be mentioned that Dr. Marchal finds that the bifurcation of the 

 seminal duct as described by Cheshire is non-existent. 



The arboreal species of wasps do not form special cells for the 

 queen larvae, but the existing small ones are increased in height, and, 

 in consequence of their shape, also in diameter. 



An evolutionary series in nest economy is thus presented, 

 commencing with Polistes, and passing, by the arboreal and then the 

 terrestrial wasps, to the honey-bee. 



An observation of great interest consists in the establishment by 

 experiment of the inability, despite desire, of male Vespa geymanica to 

 copulate with female V. vulgaris, or vice versa. This fact at once 

 demonstrates the importance of the male genital armature in deter- 

 mining species. 



En passant the immunity of the parasitic fly Volucella zonaria is 

 attributed to the quiet slow way in which it moves about within the 

 nest, in striking contrast to the behaviour of a strange wasp. 



After stating results and conclusions. Dr. Marchal proceeds to an 

 examination of Weismann's theory, and an explanation of the 

 phenomena of heredity here presented. Determinants, ids, and 

 idants are rejected as having no real existence. The 'sterility of the 

 early workers is regarded as being due (i) to insufficient food supplied 

 by the over-prolific queen, (2) to these workers having to supply food 

 to their very numerous brethren. With the advance of the season, 

 and increase in numbers of active workers, the latter become capable 

 of coping with their cares, and thus acquire more food for themselves, 

 while each larva also gets greater abundance ; thus there arises a 

 series of larger workers, some of which are fertile, and eventually 

 queens appear. Proceeding now to the effect on the germ-plasm, it is 

 maintained that the present conditions of rearing at the end of the 



