196 
Variation in Ticks 
My assumption that small forms arise through malnutrition owing 
to premature removal of the immature stages from the host has been 
confirmed by Aragao (1911-1912) 1 , who has disposed of Neumann’s 
Amblyomma cajennense var. parviscutatum by picking off nearly replete 
nymphs of A. cajennense from the host. From the imperfectly fed 
nymphs there emerged adults of small size. He thus obtained 
A. cajennense females ranging from 5'3 mm. in length (normal) down 
to 3'7 mm., i.e. a proportion of 100 : 70. He has obtained similar results 
with A. agamum. 
The variation in size observed by Aragao for Amblyomma does not 
nearly approach what I have obtained experimentally with Rhipicephalus 
appendiculatus for, in one series of observations, we removed from the 
host partially fed larvae as well as nymphs and consequently obtained 
small nymphs and small adults. 
A lot of hungry larvae (Fig. 1), the progeny of a single female, were placed upon a 
calf on 28. xi. 1912. Their subsequent history was as follows 2 : 
I- 
A | 
150 larvae, partly gorged, were picked off 
the calf on 2, 3 and 4. xn. 1912, i.e. on 
the 5-7th day. 
50 nymphs emerged on 14-18. xn. 1912 : 
metamorphosis lasted 12 days. All of 
these nymphs were placed on a calf on 
2. i. 1913. 
b] 
733 larvae, fully gorged, dropped off the 
calf on 2-7. xn. 1912, i.e. on 5-10th 
day. 
Nymphs emerged on 12-17. xn. 1912: 
metamorphosis lasted 10 days. All of 
these nymphs were placed on a calf on 
15. i. 1913. 
I- 
C I 
20 nymphs, partly 
gorged, were picked 
off calf on 6 and 
7. i. 1913, i.e. on 
the 5-6th day. 
Adults emerged on 
21-28. i. 1913 : me¬ 
tamorphosis lasted 
15 days. 
Adults: Set I. 
12 nymphs, fully 
gorged, dropped 
off calf on 7-14. i. 
1913, i.e. on the 
6-13th day. 
Adults emerged on 
23-30. 1 .1913 : me¬ 
tamorphosis lasted 
16 days. 
Set II. 
i- 
E | 
355 nymphs, partly 
gorged, were picked 
off calf on 17-24. x. 
1913, i.e. on 3-10th 
day. 
Adults began to 
emerge on 4. ii. 
1913: metamorpho¬ 
sis lasted 17 days. 
Set III. 
-[ 
F| 
148 nymphs, fully 
gorged, dropped off 
calf on 18-29. i. 
1913, i.e. on 4—15th 
day. 
Adults emerged on 
5-16. ii. 1913; me¬ 
tamorphosis lasted 
17 days. 
Set IV. 
It Avill be seen from the foregoing record that the larvae were 
allowed to feed either (A) partially, or (B) to repletion upon the host; 
that the nymphs which developed from partially fed larvae (A) were in 
turn allowed to feed (C) partially, or (D) to repletion; and that the 
1 Aragao, H. de B. (1912), “ Beitrage zur Systematik und Biologie der Ixodidae.” 
Mem. do Inst. Oswaldo Cruz, iv. 96-119, 2 pis., 6 text-figs. 
2 The ticks were all maintained at the same temperature (64-70° F.) during meta¬ 
morphosis and raised, enclosed in bags, upon the ears of calves housed in a warmed stall 
(56-60° F.). Only the minimum periods of time required for metamorphosis are stated. 
