184 REPORT OF THE DEPARTMENT OF BOTANY OF THE 
make germination tests.2> Usually, plump, bright, greenish-yellow 
seed may be depended upon to germinate well. Brown seed should 
be avoided. Brownness is an indication of age. It is hastened by 
exposure to light. Shriveled, dark-brown seeds are usually dead. 
Plump brown seeds, on the contrary, may germinate fairly well, 
for plump seeds retain their viability for several years. Of 100 
plump brown seeds selected by the writers from a sample of un- 
known age, 90 germinated. In tests made by Headden** a sample 
of prime seed 12 years old showed a germination of 93.66 per ct. 
while another sample 16 years old gave 63 per ct. 
In this connection it is interesting to note that while, according 
to Headden,”® 70,000 to 650,000 plants per acre constitute a good 
stand of alfalfa it is considered necessary to sow from 10 to 100 
times that many seeds per acre. From 20 to 30 lbs. of seed per 
acre 1s the quantity recommended in New York, the majority of 
experts favoring the larger amount. The number of seeds con- 
tained in a pound of alfalfa is variously stated by different investi- 
gators. Probably, the figures given by Nobbe”® are as reliable as 
any. le tested 47 samples of commercial seed in Germany and 
found the average number of seeds per pound to be 225,014. Our 
own work on ghis subject consists of an examination of six sam- 
ples of prime seed offered for sale at different places in New York. 
Preparation of the samples for counting consisted in shaking them 
well in the 20x20 mesh sieve recommended for removing 
dodder (see page 194) and afterward removing by hand such im- 
purities as would not pass through the sieve. The results of the 
counts were as follows: 
Sample No. I 5 gms. pure seed contained 2272 seeds—206115 per lb. 
ee ec 2 5 ve zs ce ‘ 2281 sé —=206932 iT) is 
“e 3 5 ‘e ce te “ec 2316 ae 210106 e ce 
sé 4 10 a ce ce ce 4935 se 223851 ee sé 
ce 5 10 ce te “ as 4938 ce —=223087 ins ce 
6 10 ae te é ae 5166 te 234329 ae & 
Average of six samples, 217,545 seeds per pound. 
From these figures it will be seen that in 30 lbs. of prime alfalfa 
seed there are over 6,000,000 individual seeds. Either the seed 
“On this point see Roberts and Freeman (83, p. 61). 
**Headden (41). * Headden (40, p. 40). 
“ Nobbe (73, p. 501): 
