SPECIES A^D SUBSPECIES. 231 



ments and of the observed results. In a question of the permanence or 

 mutability of forms, we may safely reason from analogy after a few 

 cases have been fully proved. A much greater eifect would, there- 

 fore, have been produced by a few detailed numerical statements, 

 than by hundreds of vaguely reported observations. Though we 

 are assured in the introductory part of the work that it contains 

 nothing hypothetical, but is based on facts that cannot be disputed, 

 when we come to investigate details we do not, in any single case, 

 get satisfactory information regarding the conditions under which 

 the observations were made. The results are in many cases opposed 

 to our ordinary experience, and to the observations of other careful 

 observers. For this reason the conditions under which they were 

 obtained should have been precisely stated, so that any one might 

 have had it in his power to repeat them. The great number of 

 plants simultaneously observed is very perplexing, and makes the 

 results still more doubtful. 



In criticising some results published by M. Caspary, on the 

 forms of some species of Biscutella, M. Jordan lays great stress on 

 the importance of taking all the precautions necessary to avoid the 

 possibility of error. AVe may, therefore, infer that he is in the habit 

 of taking every precaution which he thinks needful, but it would 

 be much more satisfactory to have some details, so that we 

 might judge for ourselves of their sufficiency. The results of M. 

 Caspary's experiment are so little in accord with M. Jordan's re- 

 sults in similar cases that he altogether refuses to accept them. 

 He quotes from the " Flora," but we find the original account of 

 these experiments in the 4th volume of Walper's " Annales." M. 

 Caspary collected the seeds of six different forms of Biscutella in 

 the autum of 1853 with great care. Sown in the spring of 1854, in the 

 Berlin Botanic Garden, each set of seeds produced a glabrous, or 

 almost glabrous, and a hairy fruited form. The smooth and hairy sorts 

 are therefore not distinct species, but are reduced by M. Caspary to 

 three. M. Jordan, on the other hand, has continued year after year 

 to raise from seed the smooth and rough-fruited forms, and has found 

 them to retain their character unaltered, as well as all the other 

 distinctive characters peculiar to each form. Looking at the matter 

 without bias, we may accept the results of both observers, the ex- 

 periments of both, so far as we can see, being equally trustworthy ; 

 but instead of saying, with M. Jordan, that Caspary's result is 

 insufficient to serve as a basis for conclusions, it seems'to us that it goes 

 far to negative any conclusions that can be founded on M. Jordan's. 



