814 



REPORT — 1894. 



•with and without calcic chloride). The chipf proteid, however, appeai-s to be of the 

 nature of nucleo-albumin (Halliburton's sodic-chloride method). Mucin is present 

 in variable anaount, and originates from the glands of the gullet below the crop. 

 The.se glands enlarge and become more active during the feeding of the young. 



The young pigeon is, then, fod at first upon a highly nutritious food, whose 

 solids consist in the main of nucleo-albamin and fiit. The explanation of this 

 peculiar process lies in all probability in the fact that since pigeons rear so many 

 broods in a season the young must be brought forward faster than could result 

 from mere grain feeding, and hence a magnificently nutrient diet is supplied. 

 When a cock or hen ' in milk ' is separated from the young the involution of the 

 crop changes occurs with great rapidity, for within twenty-four hours the temporary 

 'sebaceous glands' are loosened and cast off, the hypertrophied papillae which lie 

 between them being subsequently reduced. Such birds swallow their own ' milk ; ' 

 their villi contain more fat than normal birds, and fatty leucocytes are seen in 

 abundance in the blood. 



Some days, however, after separation, though the gross changes in the crop 

 membrane have disappeared, fatty cells are found in the epithelium. 



The ' milk' in the crops of such separated birds is also in finer particles than 

 normal and poorer in solid constituents. 



A few quantitative analyses, kindly made for me by my colleague Mr. F. J. 

 Hambly, are appended : — 



7. On the Structure of Striped Muscle. By Professor J. B. Haycraft. 



The cross-striping of muscle is due to the form of the fibril and not to its 

 internal structure. The fibril is like a beaded rod, and the striping is the optical 

 expression of this. The proof of this is obtained by stamping moist collodion 

 •with a piece of muscle. The collodion stamp preserves the form of the fibrils, 

 and shows identically the same cross-striping to tlie minutest detail. The stamps 

 and tlieir photographs were demonstrated. In one a fibril had been stamped in 

 vvliieh one part alone was in the condition of contraction, and every detail of the 

 striping, both in the relaxed and contracted conditions, was identically reproduced. 



TUESDAY, AUGUST 14. 



]. A ioint meeting with Section A was held to discuss the following Papers 

 by Professor Oliver Lodge, F.R.S. 



A. — Experiments iJhistrating Clerk Maxivell's Theory of Light. 

 B. — An Electrical Theory of Vision. 



