204 



Journal of Agricultural Research 



Vol. X, No. 4 



and 0.64 mgm. in the excrement, or a ratio of i to 0.70; in the basic lead 

 arsenate (2:50) there was 0.35 mgm. per gram of tissue and 0.53 mgm. 

 in the excrement, or a ratio of i to 1.5 1. This ratio varies somewhat in 

 the weaker strengths, but is consistent throughout, in that the amounts 

 of arsenic are higher in tne tissue and lower in the excrement in the 

 relative order as noted above. 



Table III. — Arsenic consumed by caterpillars 



VBRY SMAI,!, CATBRPn.I.ARS 



Xind and strength of solution. 



Lead hydrogen arsenate (acid) 



(2:50) 



Lead hydrogen arsenate (acid) 



(1:400) ;-\- 



Lead hydrogea arsenate (acid) 



(1:800) 



Lead hydrogen arsenate (acid) 



(i:i,20o) 



Basic lead arsenate (neutral) 



(2:50) 



Basic lead arsenate (neutral) 



(i:so) 



Basic lead arsenate (neutral) 



(1:400) 



Calcium arsenate (2:50) 



Number 

 of cater- 

 pillars. 



1,442 



3,060 



1.583 



2,510 



2,031 



2,466 



2,384 

 2, 106 



Dry caterpillars. 



Weight. 



Gm. 

 0.3130 



1. 0625 



• 7200 

 .9870 

 •5SOO 

 •S920 



I. 6520 



• 5800 



Arsenic pentoxid. 



Total. 



Mgm. 

 0.23 



Per gram 

 of tissue. 



Mgm. 

 0.74 



.19 



.18 



•15 



•31 



•39 



•17 

 .40 



Dry excrement. 



Weight. 



Gm. 

 o. 0200 



•3700 



.3400 



.4500 



. 0900 



. 0650 



1.3400 



Arsenic pentoxid. 



Total. 



Mgm. 



0.058 



.086 

 .086 



• 06s 



.058 



Per gram 

 of excre- 

 ment. 



Mgm.. 

 0.28 



•25 



•»S 

 .72 

 .89 



NEARLV MATURE CATERPILLARS 



Lead hydrogen arsenate (acid) 



(2:50) 



Lead hydrogen arsenate (acid) 



(1:50) 



Lead hydrogen arsenate (acid) 



(1:100) 



Lead hydrogen arsenate (add) 



(1:400) 



Lead hydrogen arsenate (acid) 



(1:800) 



Lead hydrogen arsenate (acid) 



(1:1,200) 



Basic lead arsenate (neutral) 



(2:50) ; 



Basic lead arsenate (neutral) 



(1:50) .^ 



Calcium arsenate (2:50) 



Calcium arsenate (1:50) 



Calcium arsenate ( i :4oo) 



Calcium arsenate (1:800) 



0.49 



•36 



• II 



.09 



.oS 



.08 



This may be explained as being due to the relative stability of the three 

 salts, since lead hydrogen arsenate and calcium arsenate are compara- 

 tively unstable compounds and would probably react more readily with 

 the body juices, permitting a large amount of the arsenic to be assimi- 

 lated and therefore retained within the tissue. The basic lead arsenate, 

 on the other hand, is a very stable salt and would probably pass through 

 the body comparatively unchanged, so that more arsenic would be found, 

 in the excrement than in the tissue. 



