X 



tation required of the newly-appointed Professor had for its title, " De 

 examine physiologico organi visus et systematis cutanei." In this dis- 

 sertation he described the now well-known method of investigating the 

 structure of the retina by the appearance seen after waving a flame beside 

 the eye. He followed out this subject in a work entitled " Observations 

 and Experiments on the Physiology of the Senses, or new Contributions to 

 the Knowledge of Subjective Vision," published in 1825. In the course of 

 the same year the Faculty of Medicine of Breslaw resolved to send their 

 congratulations to Blumenbach on the fifteenth anniversary of his doctorate, 

 accompanied by an original memoir on a suitable subject. Purkinje's offer 

 to write the memoir was gladly accepted. He took for his subject the 

 elementary origin of the bird's egg within the ovary, and its subsequent 

 progress up to the time of its deposition. This investigation, which occupied 

 him for three months, resulted in one of the most important physiological 

 discoveries of his time, that of the germinal vesicle, now generally known as 

 the " vesicle of Purkinje." The congratulatory memoir in which it was first 

 described and figured was afterwards published independently under the 

 title of " Symbolae ad ovi avium historiam ante incubationem," 1830. In 

 1828-30 he entered upon a microscopical examination of the organization 

 of plants. The elastic fibres of various vessels of plants, and the receptacles 

 of pollen and seed capsules, which scatter the pollen and the seed, especially 

 attracted his attention. The account of these researches was published in 

 1830: <c De cellulis antherum fibrosis nec non de granorum pollinarium 

 formis, commentatio phytotomica." 



On the recommendation of Mirbel, the Monthyon Prize was awarded to 

 him by the French Institute for this essay. In the spring of 1833 he un- 

 dertook the observation of the developement of the tadpole through its 

 various stages. He carefully examined the cilia which at first cover the 

 whole body, then the head, and lastly only the branches of the gills.. In 

 the course of the same year Professor Valentin began his researches on the 

 organization of the ovum of mammals, and while examining the funnel of 

 the oviduct of a rabbit, observed a movement of a granule on the mucous 

 membrane of the oviduct while floating in water, and attributed it to 

 spermatozoa. But Purkinje traced the motion to cilia on the edge of the 

 membrane. This discovery of ciliary motion in a w r arm-blooded animal 

 led to a joint research, and to the publication of the work ' De phe- 

 nomeno generali et fundamentali motus vibratorii continui in inembranis 

 cum externis turn internis animalium plurimorum et superiorum et in- 

 feriorum ordinum obvii, commentatio physiologica/ 1835. 



On entering upon his duties at Breslaw he established a physiological 

 institute in his own house, where students were furnished with the means 

 of examining microscopically the elementary parts of human bodies and 

 those of animals, and of drawing and accurately describing them. These 

 researches supplied the materials of a series of academical dissertations, 

 many of which disclosed new methods of microscopical investigation, a 

 field of research then beginning to be generally cultivated after having been 



