128 Report of Schimmel § Co. April/October 1917. 



However, no general rule can be laid down in all cases, as ants react also towards 

 complicated odours. All experiments tend to prove that their attitude depends entirely 

 whether the pomplicated odour they come in contact with is known or unknown to 

 them, whereby such terms as "known or unknown" must not be understood in the sense 

 used in the psychology of the human mind. Ants do not give any proofs of being able 

 to remember facts or of adapting themselves to unexperienced conditions. Ants have 

 quite conformed themselves to the surrounding conditions of their existence; graduated 

 forms of sensitiveness do not appeal to them and their attitude is completely governed 

 by the sum of nervous reactions they are accustomed to ; they are quite unable to show 

 a combined reaction towards any two complex stimulations acting simultaneously which 

 would take both into account. 



A second appendix treats of the various kinds of taste. In the same manner as a 

 prism is employed as a fundamental model for various odours so in this case a tetrahedron 

 is used for classifying the manifold forms of taste. One imagines the 4 different forms 

 of taste, salt, sweet, sour, and bitter, to be placed at its corners, whereas transitional 

 impressions must be sought for between the corners. The fundamental difference between 

 the psychical impression produced by various tastes in distinction to that excited by 

 various odours consists therein that the former are by no means so easily characterized 

 and defined as the latter. 



On the sense of smell and on odoriferous substances in the animal world. — G. Rorig 1 ) 

 has continued an article under this denomination of which we already discussed 2 ) the 

 first part in our last Report. He mentions several cases of the marvellous smelling 

 sense of insects which enables them either to find sources of food or influences the 

 females in finding the right spot to deposit their eggs. For instance an ichneumon-fly 

 (Rhyssa persuasoria) bores its eggs into the larva? of the tailed wasps belonging to the 

 genus sirex which live deep down in passages they gradually perforate in living trees 

 whence no trace of their presence is betrayed outside. In spite of this secluded exis- 

 tence, the Rhyssa female knows how to find them and her sense of smell is so wonder- 

 fully developed that she buries her sting into the right spot of the larvas-body which 

 is often separated from her by a woodden partition even 3 cm. thick. 



Of course errors occur at times which, however, prove absolutely that insects, in 

 depositing their eggs, are guided by their smelling power. Such a case is that of the 

 grey blue-bottle Sarcophagd carnaria which places its eggs not only on putrescent 

 bodies of animals and on putrid meat, but frequently also on the leaves of the 

 asclepiadacea Stapelia hirsuta, because the latter give off a smell of carrion; of course, 

 in this case the larvae on creeping out are doomed to perish miserably. 



The sense of smell in mammalia plays an important part in enabling the mother- 

 animal to recognise its offspring. Every herd of sheep in which the ewes live together 

 with their lambs affords abundant proof of this fact, as the lambs try to suck all the 

 ewes without any discrimination, whereas the latter only recognise their own offspring 

 and butt off all the rest. Evidently, this discriminating sense of smell is not developed 

 in the lambs, but the old ewes recognise their young however mixed up they are, and 

 in point of fact by their sense of smell, as one can easily convince oneself by 

 testing them. One has also observed in the case of the bear-seals (Ar otocephalus ursinus) 

 which congregate shortly before the termination of the whelping period in thousands 

 on the Pribiloff Islands that the females are capable of distinguishing their own offspring 



l ) Deutsche Parf.-Ztg. 8 (1916), 258, 274. — 2 ) Ibidem 8 (1916), 214; Eeport Oktober 1916, 105. 



