28 DR. C. G. SELIGMANN AND MR. S. G. SHATTOCK ON THE 
like bodies, apparently obsolete spermatozoa, possibly the residues of a 
previous state of activity. 
October 25th. Full winter plumage. 
Testes 15 mm. in chief diameter. Tubuli of medium size; furnished with 
a layer of basal cells, central to which lies a mass of cells filling the lumen of 
the tube. No spermatogenesis. 
October 27th. Full winter plumage. 
Testes about 15 mm. in longer diameter. Tubuli small, a narrow lumen in 
most. Cells averaging two deep. No spermatogenesis. 
November 1st. Full winter plumage. 
Testes 12 mm. in longer diameter. Tubuli narrow, with fine lumen. No 
spermatogenesis. 
November 7th. Full winter plumage. 
Testes about the size of a haricot. Tubuli of medium size; full of cells; 
no lumen; no spermatogenesis ; some mitoses in the more central cells. 
November 17th. Full winter plumage. 
The testes fairly firm, exuding no fluid on section; together they weighed 
5920 mg. Tubuli of medium size; fullof cells; nolumen; no spermatogenesis. 
November 28th. Full winter plumage. 
Testes yellowish; exuded no juice on section; weighed together 720 mg. 
No spermatozoa. Tubulismall, well-defined lumen. Cells average two deep. 
December 6th. Full winter plumage. 
Both testes of medium size, and showing active mitosis. 
From the foregoing table, which details the condition of the 
testes In a series of birds examined throughout the year, and the 
state of their plumage, the following summary may be made :— 
The testes attain their maximum size during the breeding- 
season, 2. ¢. at the end of March or beginning of April. At this 
time each gland is almost as large as a pigeon’s egg, and so soft 
as to be nearly diffluent on section, while the juice which exudes 
contains enormous numbers of spermatozoa. Although this con- 
dition is more or less maintained during the first half of May, by 
the end of that month the glands present a very different 
appearance. Although the birds are still in full winter plumage, 
the testes have shrunken to the size of a haricot bean; no mitotic 
figures are encountered in the cells of the tubuli, and spermato- 
genesis has ceased ; or, if any spermatozoa are to be found, these 
are badly stained and obsolete. During June the glands become 
smaller and firmer, and the whole microscopic picture is one 
of inactivity ; they diminish still further in size during July and 
August, and acquire a yellow or brownish colour. This condition 
persists throughout September, during which month the bird 
