THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. YII. Washington, D, C, December, 1886. No. 12. 



Hydra. — A Sketch of its Structure, 

 Habits, and Life History.* 



BY A. H. BRECKENFELD. 



Among the many noteworthy 

 achievements of that pioneer micro- 

 scopist, Antony van Leenwenhoek, 

 was his discovery of the remarkable 

 Httle creatures, commonly .called 

 ' fresh-water polypes,' which have, 

 since that time, received so much at- 

 tention from microscopical observers. 

 His announcement thereof, dated 

 Christmas Day, 1702, appeared in the 

 '• Philos. Transactions of the Royal 

 Society'' for January and February, 

 1703, in which, in the quaint lan- 

 guage of that olden time, he describes 

 the novel appearance and plant-like 

 'budding' of these animals. f For 

 some reason, however, the discovery 

 attracted but little attention, and 

 gradually lapsed into almost complete 

 oblivion. But in the summer of 1 740, 

 the animal was practically redis- 

 covered by Trembley, a Genevan 

 naturalist. The investigations of 

 Leenwenhoek had not come under 

 Trembley's notice, so that when he 

 first observed the presence of Hydrce 

 he was deceived by their plant-like 

 appearance, and regarded them as 

 belonging to the vegetable kingdom. 

 After observing them more closely, 

 however, their remarkable contractile 

 powers excited his surprise, and he 

 then entered upon a series of experi- 

 ments to determine the question of 



* Read before the San Francisco Microscopical So- 

 ciety, July 28th, 1886. 



t By the courtesy of the managers of the Mechanics' 

 Institute of San Francisco, whose library contains a 

 full set of the ' Transactions,' etc., I was permitted to 

 photograph the original delineation oi Hydra as made 

 by Leenwenhoek's ' limner.' From the negative thus 

 taken fig. 26 was photo-engraved. 



their proper classification. The re- 

 sults obtained were so wonderful and 

 so contradictory, that they only served 

 to increase his perplexity, and finally 

 he sent some living specimens, to- 

 gether with an account of his investi- 

 gations, to the eminent naturalist, 

 Reaumur, and the latter decided that 

 the remarkable little organisms were 

 animals. Although his doubts on 

 that score were now removed, Trem- 

 bley unremittingly pursued his re- 

 searches with special reference to the 

 polype's truly remarkable power of 

 reproducing lost parts, which pecu- 

 liarity he was the first to investigate. 

 From time to time he communicated 

 the results obtained to other observers, 

 and the enthusiasm with which he 

 studied and wrote seemed contagious, 

 for his researches excited the greatest 

 interest throughout Europe. Cuvier, 

 the great naturalist, speaks of him as 

 ' immortalized by his discovery of the 

 reproduction of the polype.' His in- 

 vestigations were soon verified by 

 eminent scientific men in other coun- 

 tries, and, in 1743, Henry Baker, a 

 Fellow of the Royal Society of Lon- 

 don, published a ' Natural History 

 of the Polype^' in which he intro- 

 duces the subject as follows : — ' The 

 accounts we have been favored with 

 from abroad concerning the little 

 creature called a polype, have ap- 

 peared so extraordinary, so contrary 

 to the common course of nature and 

 our received opinions of animal life, 

 that many people have looked upon 

 them as ridiculous whims and absurd 

 impossibilities.' He then proceeds 

 at great length, to confirm the experi- 

 ments of Trembley, and records many 



