136 B. T. LOWNE ON SO-CALLED SPONTANEOUS GENERATION. 



Pangenesis we owe it, that we have the clearest and most syste- 

 matic resume of the many wonderful phenomena of reproduction 

 and inheritance that has yet appeared ; and against the guarded 

 entertainment of the hypothesis, or speculation if you will, as a 

 means of correlating these phenomena, nothing can be urged in 

 the present state of science. The President of the Linnean Society, 

 a proverbially cautious naturalist, thus well expresses his own 

 ideas of Pangenesis — ' If,' he says, ' we take into consideration 

 how familiar mathematical signs and symbols make us with num- 

 bers and combinations, the actual realization of which is beyond all 

 human capacity ; how inconceivably minute must be those emana- 

 tions which most powerfully affect our sense of smell and our con- 

 stitutions ; and if, discarding all preventions, we follow Mr. Dar- 

 win, step by step, in applying his suppositions to the facts set before 

 us, we must, I think, admit that they may explain some, and are 

 not incompatible with others ; and it appears to me that Pangenesis 

 will be admitted by many as a provisional hypothesis, to be further 

 tested, and to be discarded only when a more plausible one shall be 

 brought forward. 1 " 



I have brought the subject of Pangenesis before you to-night 

 because I believe I have observed certain very remarkable changes 

 in the tissues of the larva of the fly prior to the formation of the 

 perfect insect, which have prepared me to believe it is possible 

 that organs or organisms are sometimes developed by aggregation 

 of excessively minute gemmules, such as those which Mr. Darwin's 

 hypothesis demands. 



From observation which I made upon this subject, I found that 

 the semi-fluid cellular matter, from which the fly is developed, is 

 derived partly from the disintegrated tissues of the larva, and partly 

 from the fat bodies or omenta. 



After the larva ceases to feed, the tissues begin to degenerate. 

 The muscles may be observed at this time in a state of continuous 

 activity, rythmic contractions commencing at one extremity of each 

 set of fibres, and passing regularly with a wave-like motion to the 

 opposite extremity. At the same time, large bright nuclei, l-1000th 

 of an inch in diameter, appear in rows in the centre of the muscular 

 fibres. These are ultimately set free by the degeneration and waste 

 of the muscles, and exhibit a granular appearance, but are readily' 

 distinguished by their great transparency and low refractive power. 



At the same time a series of remarkable changes take place in 



