494 A. W. BELLAMY 
stages—usually late cleavage stages. The eggs have much the same 
appearance as those treated in m/1000 KNC. The eggs will continue 
development, however, if they are removed to water or to lower con- 
centrations of cyanide. For instance, in experiment KNC-C.6, 
where eggs undergoing the first cleavage were exposed to the follow- 
ing concentrations of KNC: m/5000 24 hours, m/10,000 24 hours, 
m/20,000 24 hours, m/50,000 12 hours, reached late yolk plug stages. 
The yolk plugs were large and protruded considerably. In many cases 
the yolk plugs were: elongated in the median plane, i.e., elliptical in 
outline. Even with the preliminary treatment of 24 hours in m/1000 
KNC, then 24 hours in m/20,000, 12 hours in m/50,000, and 24 hours 
in m/100,000 (experiment KNC H6—eggs from same lot as above), 
equatorial gastrulae are formed somewhat similar to those produced 
in m/500,000 HgCl,—24 hours in the solution and 24 hours in water,’ 
and to those produced in LiCl—48 hours’ exposure to m/10. A few 
eggs from this lot were similar to the ‘secondary invagination’ forms 
obtained frequently in m/10 LiCl after 48 hours’ exposure.’ In 
m/20,000 KNC development is retarded and the inhibition is differ- 
ential, but very few extreme modifications are seen. 
Potassium cyanide 
Experiment ANC-C. 10. Eggs from the same female and in two- 
cell stage were divided into two lots and treated as follows in m/20,000 
KNC: 
Lot A. (a) 48 hours in KNC. Mostly advanced yolk plug stages, 
much like control. There is, however, a slight retardation of the dor- 
sal lip region. 
(b) 4 days in KNC. The embryos range all the way from” 
late blastula and early gastrula stages to closed blastopore and early 
neural fold stages—mostly the latter. A few embryos of the spina 
bifida type. Control: elongated embryos with distinct heads. 
(c) 6 days in KNC.  Blastopore has closed in most of the 
embryos. Body still round or only beginning to elongate. A few 
spina bifida present. 
(d) 8 days in KNC. Nearly normal in form, though develop- 
ing slower than control. Many dying after hatching. Ten to 20 per 
cent of the embryos spina bifida. 
(e) 9 days in KNC. Little or no further advance. Sixty 
to 70 per cent dead or dying. Heads range from about normal to 
distinctly small or retarded. 
Lot B. (a) 4 days in KNC, plus 2 days in water. Nearly all of 
the embryos elongating; head becoming distinct. All less advanced 
than control. Many of the embryos show differential recovery dis- 
tinctly as shown by the relatively advanced condition of the head and 
in some case of the tail buds. 
7 See figure 14, previous report. 
8 See previous report, figure 18. 
