IIEPWORTH, ON THE MICROSCOPE. 109 



were met with. In the livingj species of C*. Wighamii, the endochromc 

 was seen of a green colour, and aggregated in the centre of each frustule, 

 in the manner represented in the tigures of Encamjiia zodaicus, in Kutz. 

 Bac, PI. XXI., fig. 21, and Pritchard's Infusoria, PL XIII., fig. 43. No 

 appearance of conjugation has been observed, nor have we been able to 

 detect in this, or any other of the species, mentioned in this Y)aper, which 

 have come under our observation, any stria3, or markings of that kind. 



We have deterted most of the species above described in 

 guano (chiefly from Callao), and especially in Uttle transpa- 

 rent flakes or patches containing a mass of frustules. C 

 ffastridium, incurvum, Wighamii, and Peruvianum are of most 

 frequent occurrence. 



There can be little doubt that all the guano of the coast of 

 Peru is in like manner pervaded with these organisms, and if 

 so, we ought to look to this locality for living species, C. 

 Wighamii has, as we have already stated, been lately gathered 

 in Monterey Bay, and a careful search would probably bring 

 other species to light. 



The discovery of a number of specimens of C. boreale in 

 the stomach of a larue species oi Holothuria, or Sea-Cucundier, 

 should lead to tlie examination of the stomaclss of Sea-Slugs, 

 espe; ially of such as are known to feed on marine Alg<T, for 

 specimens of this singular and interesting group of Diato- 

 maceae. 



Observations on the Practical Application of the Micro- 

 scope. By J. Hkpworth, Esq. 



There are vet some parties in the medical profession who 

 are sceptical as to the utility of the microscope. I have 

 found it occasionally of practical importance ; and perhaps if 

 I mention a few cases, it may not be uninteresting to the 

 medical readers of the 'Journal.' 



J. M., a young man, aged twenty-three, applied to me, 

 bringing, in a Ijottle containing some fluid, a lock of hair, and 

 stating that he had vomited it in the night ; that he believed 

 it had been in his stomach three months, during most of 

 which he had been under medical treatment for almost con- 

 stant vomiting, and he thought this had been the cause. I 

 examined the hair, and from the fact of the bulb and sheath 

 being complete, I ccmcluded it had not been in the stomach 

 at all, or the gastric fluid would have dissolved these 

 portions of it. I suggested that it might have been thrown 

 into the vessel into which he vomited : that was found to be 

 the case, on inquiry, although he left with an impression that 



