68 



All food is iudirectly derived from the soil — that is to say, the chemical 

 constituents of the soil are tirst absorbed by the plants. The plants are 

 then eaten by the herbivorous animals (vegetable feeders), these are then 

 preyed upon by the carnivorous animals (flesh feeders), after which ranks 

 man, who is both a vegetable and flesh feeder. In the very first stages of 

 digestion or assimilation, an intermediate cause is necessary before this 

 can take place. The soil in which the plant is found must have gone 

 through some preparation before the plant can absorb the nutriment it 

 requires. This preparation is made by one of the lowest forms of 

 vegetable life, the nitrification bacillus. This organism breaks up the 

 chemical constituents of the soil, and thus provides food for the plant, 

 wliich it would be incapable of doing for itself, and hence would die of 

 starvation. In animals also a preparation has to be made, which is much 

 more complicated, before digestion can take place. It was pointed otit 

 that the lower animals had a better and more rapid digestion than man ; 

 the dog, for instance, is able to digest bones. A diagram was shown of 

 the human alimentary duct. The mouth, through which the food first 

 passes, is provided with saliva from the salivary glands, which causes the 

 conversion of starch into alkali. The food then passes into the oesophagus, 

 or gullet, where there is a sujjply of gastric or acid juice. The food next 

 passes into the intestine, where it is again met with alkaline secretion. 

 It was shown that the absence of these juices was the cause of indigestion. 

 The lecture was illustrated by numerous e.xperiments. 



Meeting held in Room No. 80, Municipal Buildings, November 17th, 

 1890. Professor L. C. Miall, F.G.S., F.L.S. (Vice-President), in the chair. 



The preliminary business included the acknowledgment of a valuable 

 series (22 in number) of pamphlets by Professor O. C. Marsh, on North 

 American PaliBontology, presented by the author, and sent direct from 

 Yale University Museum, New Haven, Coimecticut, U.S.A. 



A SKETCH OF THE LIFE-HISTORY OF SIMULIUM. 

 ARTHUR WALKER. 



Simulium belongs to the animal sub-kingdom Arthropoda in the class 

 of insects, and to the order Dijjtera. Little attention has been given to 

 this subject either by naturalists or biologists, and perhaps the only 

 liublished work worthy of reference is that of F. Meinert, a Danish writer, 

 who gives an excellent, though very brief, description of the exoskeleton 

 of the larva and pupa, but has nothing to say of its earlier stages or of the 

 internal anatomy. The eggs ai-e laid on the leaves and stems of aquatic 

 plants, watercress, water ranunculus, glyceria fluitans, &c., and in the 

 fastest part of the stream. They are of a yellowish-brown colour, 

 resembling somewhat to the unaided eye a crop of diatoms. The eggs, 

 which comprise many hundreds, are irregularly arranged and embedded in 



