752 DR JOHN RENNIE, MR PHILIP BRUCE WHITE, AND MISS ELSIE J. HARVEY 
W. No. 2 . — Tarsonemus has been known to be present in this stock since the 
beginning of August. It is now wintering, and no signs of disease have ever been 
observed. 
No. 24. — Infection from near the end of June to the beginning of September and 
not found later. Stock has not prospered. 
Re. No. 1. — Slow progress of infection. No signs of disease ; stock wintering. 
Re. No. 2. — Infection took place within three months, and the progress very slow. 
R. No. 2. — Proximity to two heavily infected stocks is a feature of this case. 
Infection probable within a month, rose in two months about 97 per cent., and the 
stock has dwindled to very small dimensions. 
W. No. 3. — Known to be infected for two months before any suspicious signs 
appeared, and these only slight in character. The stock has done well, but its 
possible survival till spring is doubtful. 
Table III. 
Date. 
Locality. 
Condition, 
of Stock. 
Numbers 
Examined. 
Tarso- 
nemus. 
Remarks. 
24 Sept. 1916 
Aberdeen 
S. 
5 
4 
Crawling bees. 
24 Apr. 1917 
Rubislaw 
S. 
1 
1 
Development stages of parasite. 
26 „ 1917 
5 July 1917 
Glassel 
S. 
9 
8 
Stock crawling. 
Aberdeen 
S. 
1 
1 
All stages of development of parasite. 
1 Eeb. 1918 
Stoneywood 
S. 
3 
3 
„ „ 
18 July 1918 
Glassel 
S. 
1 
1 
,, „ 
11 Jan. 1919 
Aberdeen 
S. 
7 
7 
>> >> 
8 Dec. 1919 
Aberdeen 
s. 
3 
3 
Stock crawling. 
The bees referred to in the foregoing table were all obtained from stocks 
recognised as suffering from the disease. The bees had been preserved on the dates 
mentioned. The results confirm the presence of Tarsonemus in diseased bees over 
the four years 1916—20, and also make clear the important fact borne out by the 1920 
examinations that the breeding of Tarsonemus goes on throughout the whole year. 
General Considerations. 
For a sound appreciation of the foregoing records, and particularly of their 
diversity in detail, it is necessary that the various factors likely to be present 
affecting the course and culmination of the epizootic within the bee colony 
should be clearly set forth. 
A colony of bees consists normally of a population which particularly in summer 
is undergoing a continuous and relatively rapid change, both as regards its con- 
stituent members and also as regards the total numbers. Daily during the working 
season there is both a steady mortality and a steady increase. This latter depends 
