JOHANSEN 



respect are demonstrable in the more primitive marsupials not 

 yet subjected to such a detailed examination. 



Turning next to the placental mammals, we are, of course, 

 confronted with an even greater complexity in phylogenetic develop- 

 ment and diversity in ecology than for the marsupials. The limita- 

 tion deemed necessary in this treatment may reflect a personal 

 bias, and I do hope the subsequent discussion will give room for 

 your feelings about these problems. 



A starting point for the phylogenetic discussion of temperature 

 regulation among the placental mammals has to be the Insectivores. 

 The tenrec of Madagascar ( Gentetes ecaudatus) is probably the 

 most phylogenetic any primitive of all the placental mammals liv- 

 ing today. Eisentraut (1955, 1956b), who together with Rand (1925), 

 seems to be the only worker having experimented with temperature 

 regulation in this important species, states that the animal estivates 

 during the dry season, which corresponds to the winter season. The 

 tenrec shows in general an extraordinary labile body temperature, 

 fluctuating between 24.1 C and 34.8 C. The tenrec is a typical 

 nocturnal animal and shows a diurnal cycle of more than 10 C 

 when the air temperature changes only 3 C to 4 G. The body tem- 

 perature must thus be closely related to the activity of the animal. 

 Eisentraut notes that the animal is able to perform normal coordin- 

 ated activity at body temperatures down to 25 G. It is unfortunate 

 that no detailed study measuring other parameters than body tem- 

 peratures has yet been done on this very interesting species. Rand 

 comments briefly that two other species of tenrec s ( Hemicentetes 

 semispinosus and Setifer setosus) remain active all year around. 



Eisentraut (1956b) also reports body temperatures in two other 

 species of primitive Insectivores ( Hemiechinus auratus and Parae - 

 nhiniiR aethiopicus) . They show a range in body temperature of 

 33.4° G to 36.4° G and 31.2 C to 36.2 G respectively. We may 

 briefly comment on the extensive studies of the European hedge- 

 hog, particularly referring to its hibernating ability. Most authors 

 report a rather large lability in the body temperature of this species, 

 from 31.2 G to 36.5 G. Morrison (19 57) has argued that this great 

 range in all probability results from measurements taken in the 



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