160 NOTES AND MEMORANDA. 



disappearance then creates between the sporiferous internal sac and 

 the wall of the sijorangium the internal cavity of the urn, crossed by 

 filaments which come from the wall. 



7th. The peristome belongs by its origin to the amphithecium. 

 The pi'imary number of its teeth is four, corresponding to the four 

 quadrants of the transversal section, in which the radial septa alter- 

 nate regularly with the periclinic septa. 



8th. In the interior of the seta and the vaginula, the cellular parti- 

 tions follow in the beginning the same laws as the segments which 

 are formed later on ; the later partitions become irregular, and trace 

 inside the tissue the first outline of the central cord. 



As to the ferns, the author has studied Pteris serrulata, an As2Ji- 

 dium, Adiantum cuneatum, and Gymnogramma chrysophylla. He differs 

 from Hofraeister in that he considers, in the quadrant resulting from 

 the division of the oospore, the suspensor of the embryo as coming 

 from one of the cells near to the base of the archegonium, and the 

 root as emanating from one of the cells near to the orifice. * He 

 supposes, moreover, that notwithstanding the fundamental differences 

 which characterize its development, the embryo of the ferns corre- 

 sponds to that of the mosses. No doubt the first septum is horizontal 

 in the oospore of the mosses, and vertical or nearly so in that of the 

 ferns ; but in the opinion of the author that would be owing to a 

 torsion of the embryo of the ferns. This is nothing more than an 

 hypothesis. | 



The "Micro-Megascope."— This is the name given by Dr. 

 Matthews to an apparatus that he has devised for exhibiting objects 

 (such as sections of jaws, the foot of a frog, insects, &c.) which are 

 too large to be viewed by the lowest object-glasses, the field of the 

 5-inch and 4-inch being respectively only ^^ and y*j of an inch. They 

 can first be reduced and examined by the apparatus as a whole, and 

 any portion of them may then, by a readjustment of the objectives, be 

 magnified as in an ordinary Microscope. The object is placed before 

 a large condensing lens (on the opposite side being the source of light), 

 and its image thrown upon the mirror, or preferably upon a prism, 

 the reflected aerial image, formed by an objective placed in the sub- 

 stage, being examined by the object-glass as the object. By this 

 meaus the range of the Microscope is extended illimitably, as the 

 object can be placed at different distances. Dr. Matthews claims that 

 the instrument may rank higher than a " toy," though as a toy it is 

 capable of producing very novel and pleasing effects. His attention 

 was directed to the method by observing the image formed by the 

 areolations in the valves of some of the diatoms, and the eyes of some 

 beetles, and the instrument was described and exhibited by him at 

 the February meeting of the Quekett Microscopical Club, and at the 

 recent soiree. 



* These ilifferences depend perhaps on the diversity of the subjects observed. 

 M. Jonkman, who has published in the ' liotanische Zeitung' (1878), No. 9, a 

 study of the prothallus of Marattia, has represented the root as coming from one 

 of the lower cells of the embryo. 



t 'Bull. Soc. Bot. de France,' vol. xxv. (1878) p. 121. 



