March, 1906.] Life Cycle of a Homosporous Pteridophyte. 
483 
rather small cat took four ounces of liver and running off with it 
was not seen again for three days when she seemed quite sick but 
could not be caught. A dog (No. 5) ate four ounces of liver 
showing no effect for two days when he became dull. The 
fourth day, having apparently recovered, he was given the heart 
and spleen. After about 24 hours fits of trembling affected his 
limbs, some of it still noticeable the next day, after which he 
was all right. 
All our experiments were with w'eeds gathered after many 
hard frosts and nearly all with weeds gathered from woods that 
have long been pastured without a single case of trembles, so 
far as the owners know, ever having occurred in them. In 
gathering it I did not notice a single plant that had been nipped 
off. The absence of inflammation in the animals that we 
experimented on as well as in those that contract the trembles 
in the pasture shows that the poison is not an irritant. The 
(juickness of its action and the fact that treml)ling is a char- 
acteristic effect indicate that it acts on the nervous system. 
THE LIFE CYCLE OF A HOMOSPOROUS PTERIDOPHYTE. 
John H. Schaffner. 
The Homosporous Pteridophytes constitute the lowest sub- 
kingdom of vascular plants. They and all plants above them 
have a true fibro-vascular system and true leaves and roots in 
the sporophyte generation except in a few cases where leaves or 
roots have been lost through an adaptation to some peculiar 
environment. No plants below the Homosporous Pteridophytes 
possess true leaves, roots, or vascular system. These plants are 
called homosporous because in them there is only one kind of 
nonsexual spores produced while the three higher subkingdoms 
of vascular plants have tw’o kinds of nonsexual spores and are 
thus called heterosporous. 
The known fossil record of Homosporous Pteridophytes does 
not extend below the Silurian Period although they must cer- 
tainly have flourished in jjrevious geological times. They were 
exceedingly abundant in the Devonian and Carboniferous and 
were among the important coal forming plants. Many were of 
the tree type while at present they are mostly low geophilous 
perennials, although in tropical countries tree ferns are still 
quite abundant. 
There are about 2,<S00 known living species of Homosporous 
Pteridophytes. They fall naturally into three distinct classes — 
ferns or Filices with 2,600 species, horsetails or Equiseteae with 
25 species, and lycopods or Lycopodieae with 155 species. 
