\\2 Hagedooni. * 



unless mated to aiiiinals of our mixed, cagebred strain, whereas ouly 

 one litter of fieldrats was ever obtained from a mating- between caged 

 animals. We are at a loss to account for the curious fact that the 

 fieldrats bred so much more readly in our cages in Berkeley, than they 

 did in their native country. 



Treerats bred easily in cages in Buitenzorg, but matings of field- 

 rats and treerats remained fruitless. As will be discussed when treating 

 of the fieldrat series, however, we have some reason for believing that 

 in nature such crosses do occur. One litter of three young was once 

 obtained from a fieldratfemale and a male of oui' houserat-treerat strain. 

 The rats did not live to be over a month old, but, as will be seen 

 presently, the fact of their production was rather important. 



The Javanese fieldrat is common all over the island, doing con- 

 siderable damage to crops. It is remarkably uniform throughout its 

 range. The Zoological Museum at Buitenzorg daily received several 

 shipments of rats from the most diverse points. We had the pleasure 

 occasionally to assist the director. Major On wens, to analyze the rats 

 sent in. Although houserats from different I'egions sometimes differed in 

 colour, or size, or skullcharacters, hardly any variability was ever 

 noticeable in the fieldrat material. On some of the sugarplantations, 

 lats were destroyed wholesale by the natives and brouglit in daily for 

 the premium. In some estates the daily catch frequently amounted to 

 ten thousand animals. Such a mass of animals furnishes excellent 

 material for a study of the vaiiability. Very seldom aberrant rats 

 were found that were not simply treerats, or houserats oi' animals of 

 an other species. Very rarely howewer, a pale rat, or a cieam one or 

 one with a white s])ot would be observed. 



Wildcanght novelties in tlie fieldrat. 



This general al)sence of vai'ial)ility makes it more remaikal)le, that 

 on one estate one day several aberrantly coloured rats were brought 

 in. They happened to be brought in alive, five halfgrown rats of 

 approximately the same ago. The managei- was so kind as to send 

 them to Buitenzoig. They were two very pale cream rats with black 

 eyes, two very light agoutis, and one albino female with pink eyes. 

 When we left for Berkeley we had one female of each colour sent us 

 from Buitenzorg, along with our other rats. 



All three females gave offspring in our cages and permitted us to 

 study the inheritance of four characters, the cream colour, the pale 

 agouti, albiuism, and waltzing. 



