18 B. GRASSI AND A. SANDIAS. 



deficient in nitrogen, and their slowness of growth must be 

 correlated with this fact. They must certainly digest cellu- 

 lose or lignin, or both of these ternary substances. 



The mandibles of the soldiers are incapable of gnawing up 

 .wood. This explains why these forms die after a short time 

 if kept in isolation — a fact I have repeatedly established by 

 forming nests entirely of soldiers (vide infra). Nevertheless, 

 they eat wood which has been triturated by other members of 

 the colony. 



The dejecta play an important part in the nutrition of 

 Calotermes, and may be said to form the ordinary diet. 

 Lignin (by the phloroglucin reaction) and cellulose are 

 found to be present in the fseces, which appear under the 

 microscope as a very fine detritus, in which traces of fibres or 

 spiral vessels are to be made out with difficulty. They appear 

 to the naked eye as cylindrical scybala, usually a little over 

 half a millimetre, but sometimes as much as a millimetre in 

 length. Their colour varies in accordance with that of the 

 wood in which the Calotermites are living, and is commonly 

 dirty white if derived from cactus, red-brown or brown if from 

 almond, &c. The scybalum is often brown with one extremity 

 reddish, and is usually quite brown when stale. If carefully 

 examined with a lens it is seen to be prismatic rather than 

 cylindrical, owing to the impressions it receives from the rectal 

 plicse. 



Calotermites ingest this substance either fresh or old, and 

 may use it for building, either directly or after ingestion and 

 subsequent regurgitation. By prolonged observation of the 

 living animal, or by suitable examination of the contents of the 

 alimentary canal, it is easy to satisfy oneself that but a very 

 small proportion of what is ingested is regurgitated. 



The dejecta are greatly preferred at the time of elimi- 

 nation, probably because, as is obvious, they are then less dry 

 (Calotermes does not habitually drink, as I shall mention 

 later). 



In order that they may be obtained in this condition, their 

 elimination is provoked by means of the antennse and maxil- 



