THESES. JAKOB HEGYFOKY. 



ting, negative deviation a retarding effect on the arrival. („Aquila" IV. 

 p. 194.) 



This was proved also by the departure „en masse" of the Swallows, 

 after a strong negative deviation from the average, when the tempera- 

 ture suddenly fell to about -|- 5", whereas the temperature on the surface 

 of thcearth might have been as low as 0", („Aquila" 111. p. p. 145, 149 

 and „Wetterbericht zum Wegzug 1898".) 



The European depressions extend their sphere of action often as far 

 as North-Africa and thus our birds can easily arrive with the southerly 

 aircurrents prevailing on their fair side. („Aquila" X, p. 194.) 



Data of arrival regarding earlier arriving species extends over a 

 longer space of time, than that of later comers ; consequently culmination 

 develops better with the later, than with earlier comers. The Phenome- 

 non of arrival is effectuated, therefore, more slowly in the case of earlier 

 arrivals, than with the later arriving species. („Aquila" IV. p. 4.; 

 X. p. 195). 



The oscillation in arrival is more marked by the earlier arriving, than 

 by the later arriving species, no matter whether the oscillation is 

 judged according to the interval between two extreme dates, or according 

 to the mean deviation of a single year from the mean of many years. 

 This refers not only to Hungary (Ghymes), but also to Pommerania 

 (Schloss Kampen near Koslin), Livonia (Dorpat), Esthonia (Hellenorm) 

 and South Russia (Kiew). In 6 species of early arrival the absolute 

 oscilation is 39, in 8 later arriving species 21 days; the average deviation 

 in the former species is ± 7-8, in the later ± 4-2 days. (Term. Kozl. Ann. 

 1900 p. 91). 



The average deviation in the same species in different and far dis- 

 tant localities seems to be a constant quantity. The latter amounts 

 in the case of the Swallow, observed in 9 places (between 46 to 65" 

 N. Lat), to ± 3-5 4-8 days. (Term. Kozl. Ann. 1900. p. 88.). 



The oscillation in the earlier arriving species is greater than in the 

 later arriving species on account of the variation in temperature, because 



(ai 28 BE!! 



