24 INTBODUGTION TO CRYPTOGAMIC BOTANY. 



processes which occupy the attention of the investigator of the 

 vital processes of the higher vegetables. Amongst the lowest 

 vegetables he will find many facts which will give him points 

 of comparison with inmates of the animal kingdom ; he will 

 see apparent Infusoria existing as mere vegetable organs, and 

 will find them performing functions under a form which he 

 will in vain hunt for amongst the higher vegetables, and if his 

 attention be turned to those Cryptogams which more closely 

 resemble these in outward appearance, he will find a form of 

 spermatozoid so closely resembling the impregnatory bodies 

 of the higher animals, as to open his mind more strongly than 

 ever to a conviction of the intimate bond by which all the 

 members of the organised world are bound, though he may 

 not subscribe to those theories which deny the existence of 

 definite groups. There can be no question in these cases of the 

 spermatozoids being developed in perfect freedom within the 

 mother cells, and not mere appendages separated from their 

 walls, and endowed with a vital action, similar to that of the 

 cilia, so common to mucous surfaces, as many animal physiolo- 

 gists assert. Such investigations will come in aid then of those 

 relative to the development of spermatozoa in animals, and 

 similar advantages will be presented in many other instances,* 

 and consequently the cryptogamic student will be able to 

 form more exact notions as to vital action in the animal 

 and vegetable kingdoms, than are usually held by those 

 who confine their investigations to either division of the 

 organised world. Again, though spiral vessels are compara- 

 tively rare in Cryptogams, opportunities of studying their 

 development and. nature are nowhere more available than 

 amongst the Hepaticce,-f where they occur without the inter- 

 vention or attachment of any other tissue, while in Zygnema 

 the curious and multiplied spiral bands may with ease be traced 

 from the first formation of the cells in which they are developed. 

 1.5. There is another point of immense importance, which the 

 cryptogamic observer has in a peculiar degree the power of stu- 



* Martino in Ann. d. So. Nat., s6r. iii., vol. 5, p. 171, on the deve- 

 lopment of Spermatozoa in the Skate, 

 t See Henfrey Linn. Tr., vol. 21, p. 103. 



