174 DEPARTMENT OF AGKICULTUEE. 



is only negative evidence. The spores of these minute fungi, when they exist, are gener 

 ally in great abundance, and may be wafted about by winds and carried by rains into 

 rivers and pools of surface water which the animals drink. The modus operandi of these 

 subtle agents of mischief, (semina morborum,) and the manner in which they gain access 

 to the animal system, have long baffled the scrutiny of scientific men. To establish the 

 fact of direct agency in any of these forms of vegetation, and to trace satisfactorily the 

 connection between cause and effect, will require cumulative proof of very strong and un 

 questionable character. The phases through which they pass, and the different forms they 

 assume at various periods of their growth, suggesting an analogy with the partheno-genesis 

 (or alternation of generations) in the animal kingdom, are another element of difficulty in 

 the solution of this question. Such investigations, however, as those undertaken by the 

 New York commissioners, conducted, as they have been, in a truly scientific and philo 

 sophical spirit, must necessarily result in throwing light upon the subject, and be ultimately 

 crowned with success. 



My collection of phenogamous plants comprises about one hundred and seventy spe 

 cies. Of these about two-thirds consist of Graminece and Cyperaccce, comprising the grasses 

 proper and the rushes, sedges, and reeds, and water grasses. I am now engaged in their 

 examination, and will furnish to the Department of Agriculture a full series. Besides 

 these, I collected such lichens and mosses as I could readily obtain, specimens of which 

 will also be prepared for the Department. 



Tiecapitidation of collection made in Texas. 



Species. 



Grasses and other phenogamous plants, about 170 



Fungi, about.. 285 



Algic, about 25 



Musci and Hepaticso, about 35 



Lichens, about 35 



Total, about 500 



Respectfully submitted. 



H. W. RAVENEL. 

 Hon. HORACE CAPRON, 



Commissioner of Agriculture. 



