502 ANIMAL NATURE OF DIATOME^E. 



ment be arrested at some intermediate form, this has 

 not occurred from the want of favorable circumstances, 

 and ought not to be considered transitory. As Mon- 

 strosities are classified, to facilitate study, or lead to the 

 attainment of general notions (concetti), so I allow that 

 the transitory forms of the inferior organisms should be 

 classified, compared and, if you please, named systemati- 

 cally ; but that they ought to figure in the same rank 

 with forms permanently attained, and truly specific, I 

 can never logically allow. 



Page 7. Some regard the epidermis as a product of 

 secretion, and therefore destitute of organisation and 

 life. Recent inquiries as to secretions, prove that they 

 are accomplished by a process exactly similar to that of 

 nutrition and growth. The question is now reduced to 

 decide whether the product of epidermal secretion ceases 

 to live whilst it still forms part of the animal structure, 

 and when this change takes place. I am glad it is in my 

 power here to introduce a note I have received from the 

 learned Moses Benvenisto. 



" The epidermis, as well as the more complicated parts, 

 which derive their formation from it, and possess charac- 

 ters and functions in common with it, is certainly orga- 

 nised. But this organisation is of an inferior grade to 

 that of many other tissues, because it is simply cellular 

 and not vascular or fibrous. It is similar to the products 

 of secretion which abound in nucleate cellules, not elon- 

 gated into fibres, nor developed in canals ; but with the 

 difference, derived in part from the contact of air, in 

 part from the action of absorbent vessels, that this external 

 secretion possesses no elementary liquid to maintain the 

 cells disaggregated, floating, and inflated ; hence result 

 only cells thatare closely united, compressed, and disposed 

 in numerous superimposed layers. But I hold a middle 

 course between those who say that the epidermic sub- 

 stance is inorganic and dead, and those who will have it 

 to be existing per se, and living by a life of its own. 

 In my opinion it has an organisation, and therefore a life, 



