182 Mr. W. Wilson on the Structure and Functions 



Dimensions {continued). inches, lines. 



Length from upper teetli to beginning of second dorsal 1 8 



. first ditto 1 4 



. anal 1 3 



ventrals 1 11^ 



pectorals 8 



edge of gill-cover 75 



Diameter of tlie eye 2 



Length of snout before the eye 2 



Height of body 9 



Length of naked part of tail ; 4^ 



[To be continued.] 



XXIX. — On the Structure and Functions of the Pollen Gra- 

 nules. By William Wilson, Esq. 



In the 'London Journal of Botany^ for November 1842, the 

 results of a sedulous inquiry into the true structure and func- 

 tions of the pollen-collectors of Campanula were presented to 

 its readers ; and in the following month a letter from Arthur 

 Hill Hassall, Esq. appeared in the same Journal, directing 

 my attention to his own remarks on the same topic, published 

 in the 'Annals and Magazine of Natural History' for October 

 last. 



In acknowledging Mr. Hassall's courtesy, I beg to say that 

 I had not seen his paper, or it would have been discussed 

 when mine was written. 



Mr. Hassall has misunderstood me. I endeavoured to state 

 that the pollen granules are taken bodily into the interior 

 of the collecting hairs, and are ultimately lodged in the im- 

 bedded cavities ; but Mr. Hassall supposes that I allude only 

 to the pollen tubes. Having met with only one instance of 

 tubes from a pollen granule thus imbedded, I did not insist 

 upon it as a fact, but reserved that point for future inquiry. 



I must entirely dissent from Mr. Hassall's views. In the 

 first place, I cannot admit the propriety of terming that part 

 where the collecting hairs are found, a " stigma." He says 

 that the papillae of the stigmatic branches "resemble the hairs 

 in everything save length ;" but if the views of physiologists 

 are right, as I believe them to be, there must be an essential 

 difference between these papillce (rounded sides of vesicles of 

 cellular stigmatic tissue, according to Lindley,) and the col- 

 lectm(j hairs, concerning the anatomy of which Mr. Hassall 

 considers Brongniart to have given a satisfactory account ; for 

 the hairs are regarded by the latter as an extension of the cu- 

 ticle covering the whole surface of the style. 



In the second place, I deem it premature and hazardous. 



