March, 1906.] Life Cycle of a Homosporous Pteridopkyte. 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, soine of it still noticeable the next day, after which he 

 was all right. 



All our experiments were with weeds 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 

 quickness of its action and the fact that trembling 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 two 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 previous geological times. Thev were 

 exceedingly abundant in the Devonian and Carboniferous and 

 were among the important coal forming plants. Many were of 

 the tree t^^pe while at present they are mostly low geophilous 

 perennials, although in tropical countries tree ferns are still 

 quite abundant. 



There are about 2,800 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. 



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